Revert of Modernize SkMutex and SkSemaphore. (patchset #2 id:20001 of https://codereview.chromium.org/1947153002/ )
Reason for revert:
This CL seems to have broken the Linux x64 and Mac
bots, e.g.
https://build.chromium.org/p/chromium/builders/Linux%20x64/builds/19052
https://build.chromium.org/p/chromium/builders/Mac/builds/15151
The error appears to have something to do with new static initializers being
added.
Original issue's description:
> Modernize SkMutex and SkSemaphore.
>
> - use <atomic>
> - fuse SkMutex and SkBaseMutex
> - fuse SkSemaphore and SkBaseSemaphore
>
> Still TODO:
> - replace SK_DECLARE_STATIC_MUTEX(name) with static SkMutex name
>
> I just didn't want to bother fixing all that up until I know this CL sticks.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1947153002
>
> No public API changes.
> TBR=reed@google.com
>
> Committed: https://skia.googlesource.com/skia/+/427c2819d9237d7d7729c59238036cfc73c072ea
TBR=herb@google.com,mtklein@chromium.org,reed@google.com,bsalomon@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=609340
Review-Url: https://codereview.chromium.org/1945343003
diff --git a/src/core/SkSemaphore.cpp b/src/core/SkSemaphore.cpp
index 0646b15..da422e2 100644
--- a/src/core/SkSemaphore.cpp
+++ b/src/core/SkSemaphore.cpp
@@ -9,7 +9,7 @@
#if defined(SK_BUILD_FOR_MAC) || defined(SK_BUILD_FOR_IOS)
#include <mach/mach.h>
- struct SkSemaphore::OSSemaphore {
+ struct SkBaseSemaphore::OSSemaphore {
semaphore_t fSemaphore;
OSSemaphore() {
@@ -21,7 +21,7 @@
void wait() { semaphore_wait(fSemaphore); }
};
#elif defined(SK_BUILD_FOR_WIN32)
- struct SkSemaphore::OSSemaphore {
+ struct SkBaseSemaphore::OSSemaphore {
HANDLE fSemaphore;
OSSemaphore() {
@@ -41,7 +41,7 @@
// It's important we test for Mach before this. This code will compile but not work there.
#include <errno.h>
#include <semaphore.h>
- struct SkSemaphore::OSSemaphore {
+ struct SkBaseSemaphore::OSSemaphore {
sem_t fSemaphore;
OSSemaphore() { sem_init(&fSemaphore, 0/*cross process?*/, 0/*initial count*/); }
@@ -57,16 +57,43 @@
///////////////////////////////////////////////////////////////////////////////
-void SkSemaphore::osSignal(int n) {
- fOSSemaphoreOnce([this] { fOSSemaphore = new OSSemaphore; });
- fOSSemaphore->signal(n);
+void SkBaseSemaphore::signal(int n) {
+ SkASSERT(n >= 0);
+
+ // We only want to call the OS semaphore when our logical count crosses
+ // from <= 0 to >0 (when we need to wake sleeping threads).
+ //
+ // This is easiest to think about with specific examples of prev and n.
+ // If n == 5 and prev == -3, there are 3 threads sleeping and we signal
+ // SkTMin(-(-3), 5) == 3 times on the OS semaphore, leaving the count at 2.
+ //
+ // If prev >= 0, no threads are waiting, SkTMin(-prev, n) is always <= 0,
+ // so we don't call the OS semaphore, leaving the count at (prev + n).
+ int prev = sk_atomic_fetch_add(&fCount, n, sk_memory_order_release);
+ int toSignal = SkTMin(-prev, n);
+ if (toSignal > 0) {
+ this->osSignal(toSignal);
+ }
}
-void SkSemaphore::osWait() {
- fOSSemaphoreOnce([this] { fOSSemaphore = new OSSemaphore; });
- fOSSemaphore->wait();
+static SkBaseSemaphore::OSSemaphore* semaphore(SkBaseSemaphore* semaphore) {
+ return semaphore->fOSSemaphore.get([](){ return new SkBaseSemaphore::OSSemaphore(); });
}
-SkSemaphore::~SkSemaphore() {
- delete fOSSemaphore;
+void SkBaseSemaphore::osSignal(int n) { semaphore(this)->signal(n); }
+
+void SkBaseSemaphore::osWait() { semaphore(this)->wait(); }
+
+void SkBaseSemaphore::deleteSemaphore() {
+ delete (OSSemaphore*) fOSSemaphore;
}
+
+///////////////////////////////////////////////////////////////////////////////
+
+SkSemaphore::SkSemaphore(){ fBaseSemaphore = {0, {0}}; }
+
+SkSemaphore::~SkSemaphore() { fBaseSemaphore.deleteSemaphore(); }
+
+void SkSemaphore::wait() { fBaseSemaphore.wait(); }
+
+void SkSemaphore::signal(int n) {fBaseSemaphore.signal(n); }
diff --git a/src/lazy/SkDiscardableMemoryPool.cpp b/src/lazy/SkDiscardableMemoryPool.cpp
index 2be4c75..1f3bcf9 100644
--- a/src/lazy/SkDiscardableMemoryPool.cpp
+++ b/src/lazy/SkDiscardableMemoryPool.cpp
@@ -29,7 +29,7 @@
/**
* Without mutex, will be not be thread safe.
*/
- DiscardableMemoryPool(size_t budget, SkMutex* mutex = nullptr);
+ DiscardableMemoryPool(size_t budget, SkBaseMutex* mutex = nullptr);
virtual ~DiscardableMemoryPool();
SkDiscardableMemory* create(size_t bytes) override;
@@ -52,9 +52,9 @@
#endif // SK_LAZY_CACHE_STATS
private:
- SkMutex* fMutex;
- size_t fBudget;
- size_t fUsed;
+ SkBaseMutex* fMutex;
+ size_t fBudget;
+ size_t fUsed;
SkTInternalLList<PoolDiscardableMemory> fList;
/** Function called to free memory if needed */
@@ -128,7 +128,8 @@
////////////////////////////////////////////////////////////////////////////////
-DiscardableMemoryPool::DiscardableMemoryPool(size_t budget, SkMutex* mutex)
+DiscardableMemoryPool::DiscardableMemoryPool(size_t budget,
+ SkBaseMutex* mutex)
: fMutex(mutex)
, fBudget(budget)
, fUsed(0) {
@@ -240,7 +241,7 @@
} // namespace
-SkDiscardableMemoryPool* SkDiscardableMemoryPool::Create(size_t size, SkMutex* mutex) {
+SkDiscardableMemoryPool* SkDiscardableMemoryPool::Create(size_t size, SkBaseMutex* mutex) {
return new DiscardableMemoryPool(size, mutex);
}
diff --git a/src/lazy/SkDiscardableMemoryPool.h b/src/lazy/SkDiscardableMemoryPool.h
index ad8d796..92ba48b 100644
--- a/src/lazy/SkDiscardableMemoryPool.h
+++ b/src/lazy/SkDiscardableMemoryPool.h
@@ -52,7 +52,8 @@
* the pool works.
* Without mutex, will be not be thread safe.
*/
- static SkDiscardableMemoryPool* Create(size_t size, SkMutex* mutex = nullptr);
+ static SkDiscardableMemoryPool* Create(
+ size_t size, SkBaseMutex* mutex = nullptr);
};
/**