mirror of
https://github.com/golang/go
synced 2024-11-20 06:54:42 -07:00
87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
|
// Copyright 2009 The Go Authors. All rights reserved.
|
||
|
|
// Use of this source code is governed by a BSD-style
|
||
|
|
// license that can be found in the LICENSE file.
|
||
|
|
|
||
|
|
// Per-P malloc cache for small objects.
|
||
|
|
//
|
||
|
|
// See malloc.h for an overview.
|
||
|
|
|
||
|
|
package runtime
|
||
|
|
|
||
|
|
import "unsafe"
|
||
|
|
|
||
|
|
// dummy MSpan that contains no free objects.
|
||
|
|
var emptymspan mspan
|
||
|
|
|
||
|
|
func allocmcache() *mcache {
|
||
|
|
lock(&mheap_.lock)
|
||
|
|
c := (*mcache)(fixAlloc_Alloc(&mheap_.cachealloc))
|
||
|
|
unlock(&mheap_.lock)
|
||
|
|
memclr(unsafe.Pointer(c), unsafe.Sizeof(*c))
|
||
|
|
for i := 0; i < _NumSizeClasses; i++ {
|
||
|
|
c.alloc[i] = &emptymspan
|
||
|
|
}
|
||
|
|
|
||
|
|
// Set first allocation sample size.
|
||
|
|
rate := MemProfileRate
|
||
|
|
if rate > 0x3fffffff { // make 2*rate not overflow
|
||
|
|
rate = 0x3fffffff
|
||
|
|
}
|
||
|
|
if rate != 0 {
|
||
|
|
c.next_sample = int32(int(fastrand1()) % (2 * rate))
|
||
|
|
}
|
||
|
|
|
||
|
|
return c
|
||
|
|
}
|
||
|
|
|
||
|
|
func freemcache(c *mcache) {
|
||
|
|
onM(func() {
|
||
|
|
mCache_ReleaseAll(c)
|
||
|
|
stackcache_clear(c)
|
||
|
|
gcworkbuffree(c.gcworkbuf)
|
||
|
|
lock(&mheap_.lock)
|
||
|
|
purgecachedstats(c)
|
||
|
|
fixAlloc_Free(&mheap_.cachealloc, unsafe.Pointer(c))
|
||
|
|
unlock(&mheap_.lock)
|
||
|
|
})
|
||
|
|
}
|
||
|
|
|
||
|
|
// Gets a span that has a free object in it and assigns it
|
||
|
|
// to be the cached span for the given sizeclass. Returns this span.
|
||
|
|
func mCache_Refill(c *mcache, sizeclass int32) *mspan {
|
||
|
|
_g_ := getg()
|
||
|
|
|
||
|
|
_g_.m.locks++
|
||
|
|
// Return the current cached span to the central lists.
|
||
|
|
s := c.alloc[sizeclass]
|
||
|
|
if s.freelist != nil {
|
||
|
|
gothrow("refill on a nonempty span")
|
||
|
|
}
|
||
|
|
if s != &emptymspan {
|
||
|
|
s.incache = false
|
||
|
|
}
|
||
|
|
|
||
|
|
// Get a new cached span from the central lists.
|
||
|
|
s = mCentral_CacheSpan(&mheap_.central[sizeclass].mcentral)
|
||
|
|
if s == nil {
|
||
|
|
gothrow("out of memory")
|
||
|
|
}
|
||
|
|
if s.freelist == nil {
|
||
|
|
println(s.ref, (s.npages<<_PageShift)/s.elemsize)
|
||
|
|
gothrow("empty span")
|
||
|
|
}
|
||
|
|
c.alloc[sizeclass] = s
|
||
|
|
_g_.m.locks--
|
||
|
|
return s
|
||
|
|
}
|
||
|
|
|
||
|
|
func mCache_ReleaseAll(c *mcache) {
|
||
|
|
for i := 0; i < _NumSizeClasses; i++ {
|
||
|
|
s := c.alloc[i]
|
||
|
|
if s != &emptymspan {
|
||
|
|
mCentral_UncacheSpan(&mheap_.central[i].mcentral, s)
|
||
|
|
c.alloc[i] = &emptymspan
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|