mirror of
https://github.com/golang/go
synced 2024-11-19 21:04:43 -07:00
53e139c7a0
Otherwise lockorder may be misaligned, since lockorder is a list of pointers and pollorder is a list of uint16. Discovered running gccgo (which uses a modified copy of this code) on SPARC. R=golang-dev, gri CC=golang-dev https://golang.org/cl/5655054
1163 lines
22 KiB
C
1163 lines
22 KiB
C
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "runtime.h"
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#include "type.h"
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#define MAXALIGN 7
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#define NOSELGEN 1
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static int32 debug = 0;
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typedef struct WaitQ WaitQ;
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typedef struct SudoG SudoG;
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typedef struct Select Select;
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typedef struct Scase Scase;
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struct SudoG
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{
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G* g; // g and selgen constitute
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uint32 selgen; // a weak pointer to g
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SudoG* link;
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byte* elem; // data element
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};
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struct WaitQ
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{
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SudoG* first;
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SudoG* last;
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};
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struct Hchan
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{
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uint32 qcount; // total data in the q
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uint32 dataqsiz; // size of the circular q
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uint16 elemsize;
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bool closed;
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uint8 elemalign;
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Alg* elemalg; // interface for element type
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uint32 sendx; // send index
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uint32 recvx; // receive index
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WaitQ recvq; // list of recv waiters
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WaitQ sendq; // list of send waiters
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Lock;
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};
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// Buffer follows Hchan immediately in memory.
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// chanbuf(c, i) is pointer to the i'th slot in the buffer.
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#define chanbuf(c, i) ((byte*)((c)+1)+(uintptr)(c)->elemsize*(i))
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enum
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{
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// Scase.kind
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CaseRecv,
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CaseSend,
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CaseDefault,
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};
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struct Scase
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{
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SudoG sg; // must be first member (cast to Scase)
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Hchan* chan; // chan
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byte* pc; // return pc
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uint16 kind;
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uint16 so; // vararg of selected bool
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bool* receivedp; // pointer to received bool (recv2)
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};
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struct Select
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{
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uint16 tcase; // total count of scase[]
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uint16 ncase; // currently filled scase[]
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uint16* pollorder; // case poll order
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Hchan** lockorder; // channel lock order
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Scase scase[1]; // one per case (in order of appearance)
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};
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static void dequeueg(WaitQ*);
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static SudoG* dequeue(WaitQ*);
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static void enqueue(WaitQ*, SudoG*);
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static void destroychan(Hchan*);
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Hchan*
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runtime·makechan_c(ChanType *t, int64 hint)
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{
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Hchan *c;
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int32 n;
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Type *elem;
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elem = t->elem;
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if(hint < 0 || (int32)hint != hint || (elem->size > 0 && hint > ((uintptr)-1) / elem->size))
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runtime·panicstring("makechan: size out of range");
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// calculate rounded size of Hchan
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n = sizeof(*c);
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while(n & MAXALIGN)
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n++;
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// allocate memory in one call
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c = (Hchan*)runtime·mal(n + hint*elem->size);
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c->elemsize = elem->size;
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c->elemalg = elem->alg;
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c->elemalign = elem->align;
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c->dataqsiz = hint;
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if(debug)
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runtime·printf("makechan: chan=%p; elemsize=%D; elemalg=%p; elemalign=%d; dataqsiz=%d\n",
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c, (int64)elem->size, elem->alg, elem->align, c->dataqsiz);
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return c;
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}
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// For reflect
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// func makechan(typ *ChanType, size uint32) (chan)
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void
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reflect·makechan(ChanType *t, uint32 size, Hchan *c)
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{
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c = runtime·makechan_c(t, size);
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FLUSH(&c);
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}
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// makechan(t *ChanType, hint int64) (hchan *chan any);
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void
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runtime·makechan(ChanType *t, int64 hint, Hchan *ret)
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{
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ret = runtime·makechan_c(t, hint);
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FLUSH(&ret);
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}
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/*
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* generic single channel send/recv
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* if the bool pointer is nil,
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* then the full exchange will
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* occur. if pres is not nil,
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* then the protocol will not
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* sleep but return if it could
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* not complete.
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*
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* sleep can wake up with g->param == nil
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* when a channel involved in the sleep has
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* been closed. it is easiest to loop and re-run
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* the operation; we'll see that it's now closed.
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*/
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void
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runtime·chansend(ChanType *t, Hchan *c, byte *ep, bool *pres)
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{
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SudoG *sg;
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SudoG mysg;
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G* gp;
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if(c == nil) {
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USED(t);
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if(pres != nil) {
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*pres = false;
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return;
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}
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g->status = Gwaiting;
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g->waitreason = "chan send (nil chan)";
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runtime·gosched();
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return; // not reached
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}
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if(runtime·gcwaiting)
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runtime·gosched();
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if(debug) {
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runtime·printf("chansend: chan=%p; elem=", c);
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c->elemalg->print(c->elemsize, ep);
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runtime·prints("\n");
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}
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runtime·lock(c);
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if(c->closed)
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goto closed;
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if(c->dataqsiz > 0)
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goto asynch;
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sg = dequeue(&c->recvq);
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if(sg != nil) {
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runtime·unlock(c);
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gp = sg->g;
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gp->param = sg;
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if(sg->elem != nil)
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c->elemalg->copy(c->elemsize, sg->elem, ep);
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runtime·ready(gp);
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if(pres != nil)
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*pres = true;
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return;
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}
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if(pres != nil) {
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runtime·unlock(c);
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*pres = false;
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return;
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}
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mysg.elem = ep;
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mysg.g = g;
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mysg.selgen = NOSELGEN;
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g->param = nil;
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g->status = Gwaiting;
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g->waitreason = "chan send";
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enqueue(&c->sendq, &mysg);
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runtime·unlock(c);
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runtime·gosched();
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if(g->param == nil) {
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runtime·lock(c);
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if(!c->closed)
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runtime·throw("chansend: spurious wakeup");
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goto closed;
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}
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return;
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asynch:
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if(c->closed)
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goto closed;
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if(c->qcount >= c->dataqsiz) {
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if(pres != nil) {
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runtime·unlock(c);
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*pres = false;
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return;
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}
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mysg.g = g;
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mysg.elem = nil;
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mysg.selgen = NOSELGEN;
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g->status = Gwaiting;
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g->waitreason = "chan send";
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enqueue(&c->sendq, &mysg);
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runtime·unlock(c);
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runtime·gosched();
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runtime·lock(c);
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goto asynch;
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}
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c->elemalg->copy(c->elemsize, chanbuf(c, c->sendx), ep);
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if(++c->sendx == c->dataqsiz)
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c->sendx = 0;
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c->qcount++;
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sg = dequeue(&c->recvq);
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if(sg != nil) {
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gp = sg->g;
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runtime·unlock(c);
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runtime·ready(gp);
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} else
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runtime·unlock(c);
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if(pres != nil)
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*pres = true;
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return;
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closed:
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runtime·unlock(c);
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runtime·panicstring("send on closed channel");
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}
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void
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runtime·chanrecv(ChanType *t, Hchan* c, byte *ep, bool *selected, bool *received)
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{
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SudoG *sg;
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SudoG mysg;
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G *gp;
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if(runtime·gcwaiting)
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runtime·gosched();
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if(debug)
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runtime·printf("chanrecv: chan=%p\n", c);
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if(c == nil) {
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USED(t);
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if(selected != nil) {
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*selected = false;
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return;
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}
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g->status = Gwaiting;
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g->waitreason = "chan receive (nil chan)";
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runtime·gosched();
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return; // not reached
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}
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runtime·lock(c);
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if(c->dataqsiz > 0)
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goto asynch;
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if(c->closed)
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goto closed;
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sg = dequeue(&c->sendq);
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if(sg != nil) {
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runtime·unlock(c);
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if(ep != nil)
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c->elemalg->copy(c->elemsize, ep, sg->elem);
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gp = sg->g;
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gp->param = sg;
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runtime·ready(gp);
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if(selected != nil)
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*selected = true;
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if(received != nil)
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*received = true;
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return;
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}
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if(selected != nil) {
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runtime·unlock(c);
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*selected = false;
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return;
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}
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mysg.elem = ep;
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mysg.g = g;
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mysg.selgen = NOSELGEN;
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g->param = nil;
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g->status = Gwaiting;
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g->waitreason = "chan receive";
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enqueue(&c->recvq, &mysg);
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runtime·unlock(c);
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runtime·gosched();
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if(g->param == nil) {
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runtime·lock(c);
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if(!c->closed)
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runtime·throw("chanrecv: spurious wakeup");
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goto closed;
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}
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if(received != nil)
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*received = true;
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return;
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asynch:
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if(c->qcount <= 0) {
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if(c->closed)
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goto closed;
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if(selected != nil) {
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runtime·unlock(c);
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*selected = false;
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if(received != nil)
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*received = false;
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return;
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}
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mysg.g = g;
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mysg.elem = nil;
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mysg.selgen = NOSELGEN;
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g->status = Gwaiting;
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g->waitreason = "chan receive";
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enqueue(&c->recvq, &mysg);
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runtime·unlock(c);
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runtime·gosched();
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runtime·lock(c);
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goto asynch;
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}
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if(ep != nil)
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c->elemalg->copy(c->elemsize, ep, chanbuf(c, c->recvx));
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c->elemalg->copy(c->elemsize, chanbuf(c, c->recvx), nil);
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if(++c->recvx == c->dataqsiz)
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c->recvx = 0;
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c->qcount--;
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sg = dequeue(&c->sendq);
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if(sg != nil) {
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gp = sg->g;
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runtime·unlock(c);
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runtime·ready(gp);
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} else
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runtime·unlock(c);
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if(selected != nil)
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*selected = true;
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if(received != nil)
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*received = true;
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return;
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closed:
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if(ep != nil)
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c->elemalg->copy(c->elemsize, ep, nil);
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if(selected != nil)
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*selected = true;
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if(received != nil)
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*received = false;
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runtime·unlock(c);
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}
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// chansend1(hchan *chan any, elem any);
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#pragma textflag 7
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void
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runtime·chansend1(ChanType *t, Hchan* c, ...)
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{
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runtime·chansend(t, c, (byte*)(&c+1), nil);
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}
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// chanrecv1(hchan *chan any) (elem any);
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#pragma textflag 7
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void
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runtime·chanrecv1(ChanType *t, Hchan* c, ...)
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{
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runtime·chanrecv(t, c, (byte*)(&c+1), nil, nil);
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}
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// chanrecv2(hchan *chan any) (elem any, received bool);
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#pragma textflag 7
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void
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runtime·chanrecv2(ChanType *t, Hchan* c, ...)
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{
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byte *ae, *ap;
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ae = (byte*)(&c+1);
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ap = ae + t->elem->size;
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runtime·chanrecv(t, c, ae, nil, ap);
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}
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// func selectnbsend(c chan any, elem any) bool
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//
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// compiler implements
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//
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// select {
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// case c <- v:
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// ... foo
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// default:
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// ... bar
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// }
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//
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// as
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//
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// if selectnbsend(c, v) {
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// ... foo
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// } else {
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// ... bar
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// }
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//
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#pragma textflag 7
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void
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runtime·selectnbsend(ChanType *t, Hchan *c, ...)
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{
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byte *ae, *ap;
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ae = (byte*)(&c + 1);
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ap = ae + runtime·rnd(t->elem->size, Structrnd);
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runtime·chansend(t, c, ae, ap);
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}
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// func selectnbrecv(elem *any, c chan any) bool
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//
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// compiler implements
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//
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// select {
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// case v = <-c:
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// ... foo
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// default:
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// ... bar
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// }
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//
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// as
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//
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// if selectnbrecv(&v, c) {
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// ... foo
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// } else {
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// ... bar
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// }
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//
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#pragma textflag 7
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void
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runtime·selectnbrecv(ChanType *t, byte *v, Hchan *c, bool selected)
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{
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runtime·chanrecv(t, c, v, &selected, nil);
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}
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// func selectnbrecv2(elem *any, ok *bool, c chan any) bool
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//
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// compiler implements
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//
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// select {
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// case v, ok = <-c:
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// ... foo
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// default:
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// ... bar
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// }
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//
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// as
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//
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// if c != nil && selectnbrecv2(&v, &ok, c) {
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// ... foo
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// } else {
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// ... bar
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// }
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//
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#pragma textflag 7
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void
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runtime·selectnbrecv2(ChanType *t, byte *v, bool *received, Hchan *c, bool selected)
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{
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runtime·chanrecv(t, c, v, &selected, received);
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}
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|
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// For reflect:
|
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// func chansend(c chan, val iword, nb bool) (selected bool)
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// where an iword is the same word an interface value would use:
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// the actual data if it fits, or else a pointer to the data.
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//
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// The "uintptr selected" is really "bool selected" but saying
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// uintptr gets us the right alignment for the output parameter block.
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void
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reflect·chansend(ChanType *t, Hchan *c, uintptr val, bool nb, uintptr selected)
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{
|
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bool *sp;
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byte *vp;
|
|
|
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if(nb) {
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selected = false;
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sp = (bool*)&selected;
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} else {
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*(bool*)&selected = true;
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FLUSH(&selected);
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sp = nil;
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}
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if(t->elem->size <= sizeof(val))
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vp = (byte*)&val;
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else
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vp = (byte*)val;
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runtime·chansend(t, c, vp, sp);
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}
|
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|
|
// For reflect:
|
|
// func chanrecv(c chan, nb bool) (val iword, selected, received bool)
|
|
// where an iword is the same word an interface value would use:
|
|
// the actual data if it fits, or else a pointer to the data.
|
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void
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reflect·chanrecv(ChanType *t, Hchan *c, bool nb, uintptr val, bool selected, bool received)
|
|
{
|
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byte *vp;
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bool *sp;
|
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|
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if(nb) {
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selected = false;
|
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sp = &selected;
|
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} else {
|
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selected = true;
|
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FLUSH(&selected);
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sp = nil;
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}
|
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received = false;
|
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FLUSH(&received);
|
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if(t->elem->size <= sizeof(val)) {
|
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val = 0;
|
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vp = (byte*)&val;
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} else {
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vp = runtime·mal(t->elem->size);
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val = (uintptr)vp;
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FLUSH(&val);
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}
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runtime·chanrecv(t, c, vp, sp, &received);
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}
|
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|
|
static void newselect(int32, Select**);
|
|
|
|
// newselect(size uint32) (sel *byte);
|
|
#pragma textflag 7
|
|
void
|
|
runtime·newselect(int32 size, ...)
|
|
{
|
|
int32 o;
|
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Select **selp;
|
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|
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o = runtime·rnd(sizeof(size), Structrnd);
|
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selp = (Select**)((byte*)&size + o);
|
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newselect(size, selp);
|
|
}
|
|
|
|
static void
|
|
newselect(int32 size, Select **selp)
|
|
{
|
|
int32 n;
|
|
Select *sel;
|
|
|
|
n = 0;
|
|
if(size > 1)
|
|
n = size-1;
|
|
|
|
// allocate all the memory we need in a single allocation
|
|
// start with Select with size cases
|
|
// then lockorder with size entries
|
|
// then pollorder with size entries
|
|
sel = runtime·mal(sizeof(*sel) +
|
|
n*sizeof(sel->scase[0]) +
|
|
size*sizeof(sel->lockorder[0]) +
|
|
size*sizeof(sel->pollorder[0]));
|
|
|
|
sel->tcase = size;
|
|
sel->ncase = 0;
|
|
sel->lockorder = (void*)(sel->scase + size);
|
|
sel->pollorder = (void*)(sel->lockorder + size);
|
|
*selp = sel;
|
|
|
|
if(debug)
|
|
runtime·printf("newselect s=%p size=%d\n", sel, size);
|
|
}
|
|
|
|
// cut in half to give stack a chance to split
|
|
static void selectsend(Select *sel, Hchan *c, void *pc, void *elem, int32 so);
|
|
|
|
// selectsend(sel *byte, hchan *chan any, elem *any) (selected bool);
|
|
#pragma textflag 7
|
|
void
|
|
runtime·selectsend(Select *sel, Hchan *c, void *elem, bool selected)
|
|
{
|
|
selected = false;
|
|
FLUSH(&selected);
|
|
|
|
// nil cases do not compete
|
|
if(c == nil)
|
|
return;
|
|
|
|
selectsend(sel, c, runtime·getcallerpc(&sel), elem, (byte*)&selected - (byte*)&sel);
|
|
}
|
|
|
|
static void
|
|
selectsend(Select *sel, Hchan *c, void *pc, void *elem, int32 so)
|
|
{
|
|
int32 i;
|
|
Scase *cas;
|
|
|
|
i = sel->ncase;
|
|
if(i >= sel->tcase)
|
|
runtime·throw("selectsend: too many cases");
|
|
sel->ncase = i+1;
|
|
cas = &sel->scase[i];
|
|
|
|
cas->pc = pc;
|
|
cas->chan = c;
|
|
cas->so = so;
|
|
cas->kind = CaseSend;
|
|
cas->sg.elem = elem;
|
|
|
|
if(debug)
|
|
runtime·printf("selectsend s=%p pc=%p chan=%p so=%d\n",
|
|
sel, cas->pc, cas->chan, cas->so);
|
|
}
|
|
|
|
// cut in half to give stack a chance to split
|
|
static void selectrecv(Select *sel, Hchan *c, void *pc, void *elem, bool*, int32 so);
|
|
|
|
// selectrecv(sel *byte, hchan *chan any, elem *any) (selected bool);
|
|
#pragma textflag 7
|
|
void
|
|
runtime·selectrecv(Select *sel, Hchan *c, void *elem, bool selected)
|
|
{
|
|
selected = false;
|
|
FLUSH(&selected);
|
|
|
|
// nil cases do not compete
|
|
if(c == nil)
|
|
return;
|
|
|
|
selectrecv(sel, c, runtime·getcallerpc(&sel), elem, nil, (byte*)&selected - (byte*)&sel);
|
|
}
|
|
|
|
// selectrecv2(sel *byte, hchan *chan any, elem *any, received *bool) (selected bool);
|
|
#pragma textflag 7
|
|
void
|
|
runtime·selectrecv2(Select *sel, Hchan *c, void *elem, bool *received, bool selected)
|
|
{
|
|
selected = false;
|
|
FLUSH(&selected);
|
|
|
|
// nil cases do not compete
|
|
if(c == nil)
|
|
return;
|
|
|
|
selectrecv(sel, c, runtime·getcallerpc(&sel), elem, received, (byte*)&selected - (byte*)&sel);
|
|
}
|
|
|
|
static void
|
|
selectrecv(Select *sel, Hchan *c, void *pc, void *elem, bool *received, int32 so)
|
|
{
|
|
int32 i;
|
|
Scase *cas;
|
|
|
|
i = sel->ncase;
|
|
if(i >= sel->tcase)
|
|
runtime·throw("selectrecv: too many cases");
|
|
sel->ncase = i+1;
|
|
cas = &sel->scase[i];
|
|
cas->pc = pc;
|
|
cas->chan = c;
|
|
|
|
cas->so = so;
|
|
cas->kind = CaseRecv;
|
|
cas->sg.elem = elem;
|
|
cas->receivedp = received;
|
|
|
|
if(debug)
|
|
runtime·printf("selectrecv s=%p pc=%p chan=%p so=%d\n",
|
|
sel, cas->pc, cas->chan, cas->so);
|
|
}
|
|
|
|
// cut in half to give stack a chance to split
|
|
static void selectdefault(Select*, void*, int32);
|
|
|
|
// selectdefault(sel *byte) (selected bool);
|
|
#pragma textflag 7
|
|
void
|
|
runtime·selectdefault(Select *sel, bool selected)
|
|
{
|
|
selected = false;
|
|
FLUSH(&selected);
|
|
|
|
selectdefault(sel, runtime·getcallerpc(&sel), (byte*)&selected - (byte*)&sel);
|
|
}
|
|
|
|
static void
|
|
selectdefault(Select *sel, void *callerpc, int32 so)
|
|
{
|
|
int32 i;
|
|
Scase *cas;
|
|
|
|
i = sel->ncase;
|
|
if(i >= sel->tcase)
|
|
runtime·throw("selectdefault: too many cases");
|
|
sel->ncase = i+1;
|
|
cas = &sel->scase[i];
|
|
cas->pc = callerpc;
|
|
cas->chan = nil;
|
|
|
|
cas->so = so;
|
|
cas->kind = CaseDefault;
|
|
|
|
if(debug)
|
|
runtime·printf("selectdefault s=%p pc=%p so=%d\n",
|
|
sel, cas->pc, cas->so);
|
|
}
|
|
|
|
static void
|
|
sellock(Select *sel)
|
|
{
|
|
uint32 i;
|
|
Hchan *c, *c0;
|
|
|
|
c = nil;
|
|
for(i=0; i<sel->ncase; i++) {
|
|
c0 = sel->lockorder[i];
|
|
if(c0 && c0 != c) {
|
|
c = sel->lockorder[i];
|
|
runtime·lock(c);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
selunlock(Select *sel)
|
|
{
|
|
uint32 i;
|
|
Hchan *c, *c0;
|
|
|
|
c = nil;
|
|
for(i=sel->ncase; i-->0;) {
|
|
c0 = sel->lockorder[i];
|
|
if(c0 && c0 != c) {
|
|
c = c0;
|
|
runtime·unlock(c);
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
runtime·block(void)
|
|
{
|
|
g->status = Gwaiting; // forever
|
|
g->waitreason = "select (no cases)";
|
|
runtime·gosched();
|
|
}
|
|
|
|
static void* selectgo(Select**);
|
|
|
|
// selectgo(sel *byte);
|
|
//
|
|
// overwrites return pc on stack to signal which case of the select
|
|
// to run, so cannot appear at the top of a split stack.
|
|
#pragma textflag 7
|
|
void
|
|
runtime·selectgo(Select *sel)
|
|
{
|
|
runtime·setcallerpc(&sel, selectgo(&sel));
|
|
}
|
|
|
|
static void*
|
|
selectgo(Select **selp)
|
|
{
|
|
Select *sel;
|
|
uint32 o, i, j;
|
|
Scase *cas, *dfl;
|
|
Hchan *c;
|
|
SudoG *sg;
|
|
G *gp;
|
|
byte *as;
|
|
void *pc;
|
|
|
|
sel = *selp;
|
|
if(runtime·gcwaiting)
|
|
runtime·gosched();
|
|
|
|
if(debug)
|
|
runtime·printf("select: sel=%p\n", sel);
|
|
|
|
// The compiler rewrites selects that statically have
|
|
// only 0 or 1 cases plus default into simpler constructs.
|
|
// The only way we can end up with such small sel->ncase
|
|
// values here is for a larger select in which most channels
|
|
// have been nilled out. The general code handles those
|
|
// cases correctly, and they are rare enough not to bother
|
|
// optimizing (and needing to test).
|
|
|
|
// generate permuted order
|
|
for(i=0; i<sel->ncase; i++)
|
|
sel->pollorder[i] = i;
|
|
for(i=1; i<sel->ncase; i++) {
|
|
o = sel->pollorder[i];
|
|
j = runtime·fastrand1()%(i+1);
|
|
sel->pollorder[i] = sel->pollorder[j];
|
|
sel->pollorder[j] = o;
|
|
}
|
|
|
|
// sort the cases by Hchan address to get the locking order.
|
|
for(i=0; i<sel->ncase; i++) {
|
|
c = sel->scase[i].chan;
|
|
for(j=i; j>0 && sel->lockorder[j-1] >= c; j--)
|
|
sel->lockorder[j] = sel->lockorder[j-1];
|
|
sel->lockorder[j] = c;
|
|
}
|
|
sellock(sel);
|
|
|
|
loop:
|
|
// pass 1 - look for something already waiting
|
|
dfl = nil;
|
|
for(i=0; i<sel->ncase; i++) {
|
|
o = sel->pollorder[i];
|
|
cas = &sel->scase[o];
|
|
c = cas->chan;
|
|
|
|
switch(cas->kind) {
|
|
case CaseRecv:
|
|
if(c->dataqsiz > 0) {
|
|
if(c->qcount > 0)
|
|
goto asyncrecv;
|
|
} else {
|
|
sg = dequeue(&c->sendq);
|
|
if(sg != nil)
|
|
goto syncrecv;
|
|
}
|
|
if(c->closed)
|
|
goto rclose;
|
|
break;
|
|
|
|
case CaseSend:
|
|
if(c->closed)
|
|
goto sclose;
|
|
if(c->dataqsiz > 0) {
|
|
if(c->qcount < c->dataqsiz)
|
|
goto asyncsend;
|
|
} else {
|
|
sg = dequeue(&c->recvq);
|
|
if(sg != nil)
|
|
goto syncsend;
|
|
}
|
|
break;
|
|
|
|
case CaseDefault:
|
|
dfl = cas;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if(dfl != nil) {
|
|
selunlock(sel);
|
|
cas = dfl;
|
|
goto retc;
|
|
}
|
|
|
|
|
|
// pass 2 - enqueue on all chans
|
|
for(i=0; i<sel->ncase; i++) {
|
|
o = sel->pollorder[i];
|
|
cas = &sel->scase[o];
|
|
c = cas->chan;
|
|
sg = &cas->sg;
|
|
sg->g = g;
|
|
sg->selgen = g->selgen;
|
|
|
|
switch(cas->kind) {
|
|
case CaseRecv:
|
|
enqueue(&c->recvq, sg);
|
|
break;
|
|
|
|
case CaseSend:
|
|
enqueue(&c->sendq, sg);
|
|
break;
|
|
}
|
|
}
|
|
|
|
g->param = nil;
|
|
g->status = Gwaiting;
|
|
g->waitreason = "select";
|
|
selunlock(sel);
|
|
runtime·gosched();
|
|
|
|
sellock(sel);
|
|
sg = g->param;
|
|
|
|
// pass 3 - dequeue from unsuccessful chans
|
|
// otherwise they stack up on quiet channels
|
|
for(i=0; i<sel->ncase; i++) {
|
|
cas = &sel->scase[i];
|
|
if(cas != (Scase*)sg) {
|
|
c = cas->chan;
|
|
if(cas->kind == CaseSend)
|
|
dequeueg(&c->sendq);
|
|
else
|
|
dequeueg(&c->recvq);
|
|
}
|
|
}
|
|
|
|
if(sg == nil)
|
|
goto loop;
|
|
|
|
cas = (Scase*)sg;
|
|
c = cas->chan;
|
|
|
|
if(c->dataqsiz > 0)
|
|
runtime·throw("selectgo: shouldnt happen");
|
|
|
|
if(debug)
|
|
runtime·printf("wait-return: sel=%p c=%p cas=%p kind=%d\n",
|
|
sel, c, cas, cas->kind);
|
|
|
|
if(cas->kind == CaseRecv) {
|
|
if(cas->receivedp != nil)
|
|
*cas->receivedp = true;
|
|
}
|
|
|
|
selunlock(sel);
|
|
goto retc;
|
|
|
|
asyncrecv:
|
|
// can receive from buffer
|
|
if(cas->receivedp != nil)
|
|
*cas->receivedp = true;
|
|
if(cas->sg.elem != nil)
|
|
c->elemalg->copy(c->elemsize, cas->sg.elem, chanbuf(c, c->recvx));
|
|
c->elemalg->copy(c->elemsize, chanbuf(c, c->recvx), nil);
|
|
if(++c->recvx == c->dataqsiz)
|
|
c->recvx = 0;
|
|
c->qcount--;
|
|
sg = dequeue(&c->sendq);
|
|
if(sg != nil) {
|
|
gp = sg->g;
|
|
selunlock(sel);
|
|
runtime·ready(gp);
|
|
} else {
|
|
selunlock(sel);
|
|
}
|
|
goto retc;
|
|
|
|
asyncsend:
|
|
// can send to buffer
|
|
c->elemalg->copy(c->elemsize, chanbuf(c, c->sendx), cas->sg.elem);
|
|
if(++c->sendx == c->dataqsiz)
|
|
c->sendx = 0;
|
|
c->qcount++;
|
|
sg = dequeue(&c->recvq);
|
|
if(sg != nil) {
|
|
gp = sg->g;
|
|
selunlock(sel);
|
|
runtime·ready(gp);
|
|
} else {
|
|
selunlock(sel);
|
|
}
|
|
goto retc;
|
|
|
|
syncrecv:
|
|
// can receive from sleeping sender (sg)
|
|
selunlock(sel);
|
|
if(debug)
|
|
runtime·printf("syncrecv: sel=%p c=%p o=%d\n", sel, c, o);
|
|
if(cas->receivedp != nil)
|
|
*cas->receivedp = true;
|
|
if(cas->sg.elem != nil)
|
|
c->elemalg->copy(c->elemsize, cas->sg.elem, sg->elem);
|
|
gp = sg->g;
|
|
gp->param = sg;
|
|
runtime·ready(gp);
|
|
goto retc;
|
|
|
|
rclose:
|
|
// read at end of closed channel
|
|
selunlock(sel);
|
|
if(cas->receivedp != nil)
|
|
*cas->receivedp = false;
|
|
if(cas->sg.elem != nil)
|
|
c->elemalg->copy(c->elemsize, cas->sg.elem, nil);
|
|
goto retc;
|
|
|
|
syncsend:
|
|
// can send to sleeping receiver (sg)
|
|
selunlock(sel);
|
|
if(debug)
|
|
runtime·printf("syncsend: sel=%p c=%p o=%d\n", sel, c, o);
|
|
if(sg->elem != nil)
|
|
c->elemalg->copy(c->elemsize, sg->elem, cas->sg.elem);
|
|
gp = sg->g;
|
|
gp->param = sg;
|
|
runtime·ready(gp);
|
|
|
|
retc:
|
|
// return to pc corresponding to chosen case
|
|
pc = cas->pc;
|
|
as = (byte*)selp + cas->so;
|
|
runtime·free(sel);
|
|
*as = true;
|
|
return pc;
|
|
|
|
sclose:
|
|
// send on closed channel
|
|
selunlock(sel);
|
|
runtime·panicstring("send on closed channel");
|
|
return nil; // not reached
|
|
}
|
|
|
|
// closechan(sel *byte);
|
|
void
|
|
runtime·closechan(Hchan *c)
|
|
{
|
|
SudoG *sg;
|
|
G* gp;
|
|
|
|
if(c == nil)
|
|
runtime·panicstring("close of nil channel");
|
|
|
|
if(runtime·gcwaiting)
|
|
runtime·gosched();
|
|
|
|
runtime·lock(c);
|
|
if(c->closed) {
|
|
runtime·unlock(c);
|
|
runtime·panicstring("close of closed channel");
|
|
}
|
|
|
|
c->closed = true;
|
|
|
|
// release all readers
|
|
for(;;) {
|
|
sg = dequeue(&c->recvq);
|
|
if(sg == nil)
|
|
break;
|
|
gp = sg->g;
|
|
gp->param = nil;
|
|
runtime·ready(gp);
|
|
}
|
|
|
|
// release all writers
|
|
for(;;) {
|
|
sg = dequeue(&c->sendq);
|
|
if(sg == nil)
|
|
break;
|
|
gp = sg->g;
|
|
gp->param = nil;
|
|
runtime·ready(gp);
|
|
}
|
|
|
|
runtime·unlock(c);
|
|
}
|
|
|
|
// For reflect
|
|
// func chanclose(c chan)
|
|
void
|
|
reflect·chanclose(Hchan *c)
|
|
{
|
|
runtime·closechan(c);
|
|
}
|
|
|
|
// For reflect
|
|
// func chanlen(c chan) (len int32)
|
|
void
|
|
reflect·chanlen(Hchan *c, int32 len)
|
|
{
|
|
if(c == nil)
|
|
len = 0;
|
|
else
|
|
len = c->qcount;
|
|
FLUSH(&len);
|
|
}
|
|
|
|
// For reflect
|
|
// func chancap(c chan) (cap int32)
|
|
void
|
|
reflect·chancap(Hchan *c, int32 cap)
|
|
{
|
|
if(c == nil)
|
|
cap = 0;
|
|
else
|
|
cap = c->dataqsiz;
|
|
FLUSH(&cap);
|
|
}
|
|
|
|
static SudoG*
|
|
dequeue(WaitQ *q)
|
|
{
|
|
SudoG *sgp;
|
|
|
|
loop:
|
|
sgp = q->first;
|
|
if(sgp == nil)
|
|
return nil;
|
|
q->first = sgp->link;
|
|
|
|
// if sgp is stale, ignore it
|
|
if(sgp->selgen != NOSELGEN &&
|
|
(sgp->selgen != sgp->g->selgen ||
|
|
!runtime·cas(&sgp->g->selgen, sgp->selgen, sgp->selgen + 2))) {
|
|
//prints("INVALID PSEUDOG POINTER\n");
|
|
goto loop;
|
|
}
|
|
|
|
return sgp;
|
|
}
|
|
|
|
static void
|
|
dequeueg(WaitQ *q)
|
|
{
|
|
SudoG **l, *sgp, *prevsgp;
|
|
|
|
prevsgp = nil;
|
|
for(l=&q->first; (sgp=*l) != nil; l=&sgp->link, prevsgp=sgp) {
|
|
if(sgp->g == g) {
|
|
*l = sgp->link;
|
|
if(q->last == sgp)
|
|
q->last = prevsgp;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
enqueue(WaitQ *q, SudoG *sgp)
|
|
{
|
|
sgp->link = nil;
|
|
if(q->first == nil) {
|
|
q->first = sgp;
|
|
q->last = sgp;
|
|
return;
|
|
}
|
|
q->last->link = sgp;
|
|
q->last = sgp;
|
|
}
|