gecko-dev/js/jsd/jsd_lock.cpp

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5.2 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* JavaScript Debugging support - Locking and threading support
*/
/*
* ifdef JSD_USE_NSPR_LOCKS then you must build and run against NSPR2.
* Otherwise, there are stubs that can be filled in with your own locking
* code. Also, note that these stubs include a jsd_CurrentThread()
* implementation that only works on Win32 - this is needed for the inprocess
* Java-based debugger.
*/
#include "jsd.h"
#include "js/Utility.h"
#ifdef JSD_THREADSAFE
#ifdef JSD_USE_NSPR_LOCKS
#include "prlock.h"
#include "prthread.h"
#ifdef JSD_ATTACH_THREAD_HACK
#include "pprthred.h" /* need this as long as JS_AttachThread is needed */
#endif
struct JSDStaticLock
{
void* owner;
PRLock* lock;
int count;
#ifdef DEBUG
uint16_t sig;
#endif
};
/*
* This exists to wrap non-NSPR theads (e.g. Java threads) in NSPR wrappers.
* XXX We ignore the memory leak issue.
* It is claimed that future versions of NSPR will automatically wrap on
* the call to PR_GetCurrentThread.
*
* XXX We ignore the memory leak issue - i.e. we never call PR_DetachThread.
*
*/
#undef _CURRENT_THREAD
#ifdef JSD_ATTACH_THREAD_HACK
#define _CURRENT_THREAD(out) \
JS_BEGIN_MACRO \
out = (void*) PR_GetCurrentThread(); \
if(!out) \
out = (void*) JS_AttachThread(PR_USER_THREAD, PR_PRIORITY_NORMAL, \
nullptr); \
MOZ_ASSERT(out); \
JS_END_MACRO
#else
#define _CURRENT_THREAD(out) \
JS_BEGIN_MACRO \
out = (void*) PR_GetCurrentThread(); \
MOZ_ASSERT(out); \
JS_END_MACRO
#endif
#ifdef DEBUG
#define JSD_LOCK_SIG 0x10CC10CC
void ASSERT_VALID_LOCK(JSDStaticLock* lock)
{
MOZ_ASSERT(lock);
MOZ_ASSERT(lock->lock);
MOZ_ASSERT(lock->count >= 0);
MOZ_ASSERT(lock->sig == (uint16_t) JSD_LOCK_SIG);
}
#else
#define ASSERT_VALID_LOCK(x) ((void)0)
#endif
JSDStaticLock*
jsd_CreateLock()
{
JSDStaticLock* lock;
if( ! (lock = js_pod_calloc<JSDStaticLock>()) ||
! (lock->lock = PR_NewLock()) )
{
if(lock)
{
free(lock);
lock = nullptr;
}
}
#ifdef DEBUG
if(lock) lock->sig = (uint16_t) JSD_LOCK_SIG;
#endif
return lock;
}
void
jsd_Lock(JSDStaticLock* lock)
{
void* me;
ASSERT_VALID_LOCK(lock);
_CURRENT_THREAD(me);
if(lock->owner == me)
{
lock->count++;
MOZ_ASSERT(lock->count > 1);
}
else
{
PR_Lock(lock->lock); /* this can block... */
MOZ_ASSERT(lock->owner == 0);
MOZ_ASSERT(lock->count == 0);
lock->count = 1;
lock->owner = me;
}
}
void
jsd_Unlock(JSDStaticLock* lock)
{
void* me;
ASSERT_VALID_LOCK(lock);
_CURRENT_THREAD(me);
/* it's an error to unlock a lock you don't own */
MOZ_ASSERT(lock->owner == me);
if(lock->owner != me)
return;
if(--lock->count == 0)
{
lock->owner = nullptr;
PR_Unlock(lock->lock);
}
}
#ifdef DEBUG
bool
jsd_IsLocked(JSDStaticLock* lock)
{
void* me;
ASSERT_VALID_LOCK(lock);
_CURRENT_THREAD(me);
if (lock->owner != me)
return false;
MOZ_ASSERT(lock->count > 0);
return true;
}
#endif /* DEBUG */
void*
jsd_CurrentThread()
{
void* me;
_CURRENT_THREAD(me);
return me;
}
#else /* ! JSD_USE_NSPR_LOCKS */
#ifdef WIN32
#pragma message("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!")
#pragma message("!! you are compiling the stubbed version of jsd_lock.c !!")
#pragma message("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!")
#endif
/*
* NOTE: 'Real' versions of these locks must be reentrant in the sense that
* they support nested calls to lock and unlock.
*/
void*
jsd_CreateLock()
{
return (void*)1;
}
void
jsd_Lock(void* lock)
{
}
void
jsd_Unlock(void* lock)
{
}
#ifdef DEBUG
bool
jsd_IsLocked(void* lock)
{
return true;
}
#endif /* DEBUG */
/*
* This Windows only thread id code is here to allow the Java-based
* JSDebugger to work with the single threaded js.c shell (even without
* real locking and threading support).
*/
#ifdef WIN32
/* bogus (but good enough) declaration*/
extern void* __stdcall GetCurrentThreadId(void);
#endif
void*
jsd_CurrentThread()
{
#ifdef WIN32
return GetCurrentThreadId();
#else
return (void*)1;
#endif
}
#endif /* JSD_USE_NSPR_LOCKS */
#endif /* JSD_THREADSAFE */