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go/src/runtime/cgo.go
Srdjan Petrovic e8694c8196 runtime: initialize shared library at library-load time
This is Part 2 of the change, see Part 1 here: in https://go-review.googlesource.com/#/c/7692/

Suggested by iant@, we use the library initialization entry point to:
    - create a new OS thread and run the "regular" runtime init stack on
      that thread
    - return immediately from the main (i.e., loader) thread
    - at the first CGO invocation, we wait for the runtime initialization
      to complete.

The above mechanism is implemented only on linux_amd64.  Next step is to
support it on linux_arm.  Other platforms don't yet support shared library
compiling/linking, but we intend to use the same strategy there as well.

Change-Id: Ib2c81b1b83bee837134084b75a3beecfb8de6bf4
Reviewed-on: https://go-review.googlesource.com/8094
Run-TryBot: Srdjan Petrovic <spetrovic@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-03 01:24:51 +00:00

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Go

// Copyright 2014 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.
package runtime
import "unsafe"
//go:cgo_export_static main
// Filled in by runtime/cgo when linked into binary.
//go:linkname _cgo_init _cgo_init
//go:linkname _cgo_malloc _cgo_malloc
//go:linkname _cgo_free _cgo_free
//go:linkname _cgo_thread_start _cgo_thread_start
//go:linkname _cgo_sys_thread_create _cgo_sys_thread_create
//go:linkname _cgo_notify_runtime_init_done _cgo_notify_runtime_init_done
var (
_cgo_init unsafe.Pointer
_cgo_malloc unsafe.Pointer
_cgo_free unsafe.Pointer
_cgo_thread_start unsafe.Pointer
_cgo_sys_thread_create unsafe.Pointer
_cgo_notify_runtime_init_done unsafe.Pointer
)
// iscgo is set to true by the runtime/cgo package
var iscgo bool
// cgoHasExtraM is set on startup when an extra M is created for cgo.
// The extra M must be created before any C/C++ code calls cgocallback.
var cgoHasExtraM bool