Convert futex to cond wait.
Switch to the better supported pthread_cond to handle the Wait/Wake
functions.
Also, increase the number of simultaneous threads in the thread tests.
Bug: 18381207
Change-Id: I63240208e8b7f641b3f35a3fc0bb1acf80dc796e
diff --git a/libbacktrace/BacktraceThread.cpp b/libbacktrace/BacktraceThread.cpp
index b47cd2a..439cc3b 100644
--- a/libbacktrace/BacktraceThread.cpp
+++ b/libbacktrace/BacktraceThread.cpp
@@ -17,14 +17,15 @@
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
-#include <linux/futex.h>
#include <pthread.h>
#include <signal.h>
+#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <ucontext.h>
+#include <unistd.h>
#include <cutils/atomic.h>
@@ -32,10 +33,6 @@
#include "BacktraceThread.h"
#include "thread_utils.h"
-static inline int futex(volatile int* uaddr, int op, int val, const struct timespec* ts, volatile int* uaddr2, int val3) {
- return syscall(__NR_futex, uaddr, op, val, ts, uaddr2, val3);
-}
-
//-------------------------------------------------------------------------
// ThreadEntry implementation.
//-------------------------------------------------------------------------
@@ -45,7 +42,14 @@
// Assumes that ThreadEntry::list_mutex_ has already been locked before
// creating a ThreadEntry object.
ThreadEntry::ThreadEntry(pid_t pid, pid_t tid)
- : pid_(pid), tid_(tid), futex_(0), ref_count_(1), mutex_(PTHREAD_MUTEX_INITIALIZER), next_(ThreadEntry::list_), prev_(NULL) {
+ : pid_(pid), tid_(tid), ref_count_(1), mutex_(PTHREAD_MUTEX_INITIALIZER),
+ wait_mutex_(PTHREAD_MUTEX_INITIALIZER), wait_value_(0),
+ next_(ThreadEntry::list_), prev_(NULL) {
+ pthread_condattr_t attr;
+ pthread_condattr_init(&attr);
+ pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
+ pthread_cond_init(&wait_cond_, &attr);
+
// Add ourselves to the list.
if (ThreadEntry::list_) {
ThreadEntry::list_->prev_ = this;
@@ -99,22 +103,35 @@
next_ = NULL;
prev_ = NULL;
+
+ pthread_cond_destroy(&wait_cond_);
}
void ThreadEntry::Wait(int value) {
timespec ts;
- ts.tv_sec = 10;
- ts.tv_nsec = 0;
- errno = 0;
- futex(&futex_, FUTEX_WAIT, value, &ts, NULL, 0);
- if (errno != 0 && errno != EWOULDBLOCK) {
- BACK_LOGW("futex wait failed, futex = %d: %s", futex_, strerror(errno));
+ if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1) {
+ BACK_LOGW("clock_gettime failed: %s", strerror(errno));
+ abort();
}
+ ts.tv_sec += 10;
+
+ pthread_mutex_lock(&wait_mutex_);
+ while (wait_value_ != value) {
+ int ret = pthread_cond_timedwait(&wait_cond_, &wait_mutex_, &ts);
+ if (ret != 0) {
+ BACK_LOGW("pthread_cond_timedwait failed: %s", strerror(ret));
+ break;
+ }
+ }
+ pthread_mutex_unlock(&wait_mutex_);
}
void ThreadEntry::Wake() {
- futex_++;
- futex(&futex_, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
+ pthread_mutex_lock(&wait_mutex_);
+ wait_value_++;
+ pthread_mutex_unlock(&wait_mutex_);
+
+ pthread_cond_signal(&wait_cond_);
}
void ThreadEntry::CopyUcontextFromSigcontext(void* sigcontext) {
@@ -142,7 +159,7 @@
// Pause the thread until the unwind is complete. This avoids having
// the thread run ahead causing problems.
- entry->Wait(1);
+ entry->Wait(2);
ThreadEntry::Remove(entry);
}
@@ -194,7 +211,7 @@
}
// Wait for the thread to get the ucontext.
- entry->Wait(0);
+ entry->Wait(1);
// After the thread has received the signal, allow other unwinders to
// continue.