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rt: Fix lock_held_by_current_thread

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This simplifies the check for thread ownership by removing the _locked flag
and just comparing against the thread ID of the last thread to take the lock.
If the running thread took the lock _holding_thread will be equal to
pthread_self(); if _holding_thread is some other value then the running thread
does not have the lock.

Setting a pthread_t to 0 like this is not portable but should work on every
platform we are likely to care about for the near future.
This commit is contained in:
Brian Anderson 2012-02-01 14:54:51 -08:00
parent 6b5f7865be
commit f76e6c39f6
2 changed files with 12 additions and 8 deletions
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19
src/rt/sync/lock_and_signal.cpp
View file

@ -1,3 +1,4 @@
#include <assert.h>
#include "../globals.h" #include "../globals.h"
/* /*
@ -9,8 +10,13 @@
#include "lock_and_signal.h" #include "lock_and_signal.h"
// FIXME: This is not a portable way of specifying an invalid pthread_t
#define INVALID_THREAD 0
#if defined(__WIN32__) #if defined(__WIN32__)
lock_and_signal::lock_and_signal() lock_and_signal::lock_and_signal()
: _holding_thread(INVALID_THREAD)
{ {
// FIXME: In order to match the behavior of pthread_cond_broadcast on // FIXME: In order to match the behavior of pthread_cond_broadcast on
// Windows, we create manual reset events. This however breaks the // Windows, we create manual reset events. This however breaks the
@ -23,7 +29,7 @@ lock_and_signal::lock_and_signal()
#else #else
lock_and_signal::lock_and_signal() lock_and_signal::lock_and_signal()
: _locked(false) : _holding_thread(INVALID_THREAD)
{ {
CHECKED(pthread_cond_init(&_cond, NULL)); CHECKED(pthread_cond_init(&_cond, NULL));
CHECKED(pthread_mutex_init(&_mutex, NULL)); CHECKED(pthread_mutex_init(&_mutex, NULL));
@ -47,11 +53,10 @@ void lock_and_signal::lock() {
CHECKED(pthread_mutex_lock(&_mutex)); CHECKED(pthread_mutex_lock(&_mutex));
_holding_thread = pthread_self(); _holding_thread = pthread_self();
#endif #endif
_locked = true;
} }
void lock_and_signal::unlock() { void lock_and_signal::unlock() {
_locked = false; _holding_thread = INVALID_THREAD;
#if defined(__WIN32__) #if defined(__WIN32__)
LeaveCriticalSection(&_cs); LeaveCriticalSection(&_cs);
#else #else
@ -67,7 +72,8 @@ void lock_and_signal::wait() {
} }
bool lock_and_signal::timed_wait(size_t timeout_in_ms) { bool lock_and_signal::timed_wait(size_t timeout_in_ms) {
_locked = false; assert(lock_held_by_current_thread());
_holding_thread = INVALID_THREAD;
bool rv = true; bool rv = true;
#if defined(__WIN32__) #if defined(__WIN32__)
LeaveCriticalSection(&_cs); LeaveCriticalSection(&_cs);
@ -105,7 +111,6 @@ bool lock_and_signal::timed_wait(size_t timeout_in_ms) {
} }
_holding_thread = pthread_self(); _holding_thread = pthread_self();
#endif #endif
_locked = true;
return rv; return rv;
} }
@ -134,9 +139,9 @@ void lock_and_signal::signal_all() {
bool lock_and_signal::lock_held_by_current_thread() bool lock_and_signal::lock_held_by_current_thread()
{ {
#if defined(__WIN32__) #if defined(__WIN32__)
return _locked && _holding_thread == GetCurrentThreadId(); return _holding_thread == GetCurrentThreadId();
#else #else
return _locked && _holding_thread == pthread_self(); return pthread_equal(_holding_thread, pthread_self());
#endif #endif
} }

1
src/rt/sync/lock_and_signal.h
View file

@ -13,7 +13,6 @@ class lock_and_signal {
pthread_t _holding_thread; pthread_t _holding_thread;
#endif #endif
bool _locked;
public: public:
lock_and_signal(); lock_and_signal();