Add SkThreadPool for managing threads.
Skia-ized from https://codereview.appspot.com/6755043/
TODO: Use SkThread and platform independent features.
Review URL: https://codereview.appspot.com/6777064
git-svn-id: http://skia.googlecode.com/svn/trunk@6217 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gyp/utils.gyp b/gyp/utils.gyp
index cc25349..61cfd12 100644
--- a/gyp/utils.gyp
+++ b/gyp/utils.gyp
@@ -18,6 +18,15 @@
'../src/utils',
],
'sources': [
+ # Classes for a threadpool.
+ '../include/utils/SkCondVar.h',
+ '../include/utils/SkCountdown.h',
+ '../include/utils/SkRunnable.h',
+ '../include/utils/SkThreadPool.h',
+ '../src/utils/SkCondVar.cpp',
+ '../src/utils/SkCountdown.cpp',
+ '../src/utils/SkThreadPool.cpp',
+
'../include/utils/SkBoundaryPatch.h',
'../include/utils/SkCamera.h',
'../include/utils/SkCubicInterval.h',
@@ -147,6 +156,15 @@
'../src/utils/SkThreadUtils_pthread.cpp',
'../src/utils/SkThreadUtils_pthread.h',
'../src/utils/SkThreadUtils_pthread_other.cpp',
+
+ # SkThreadPool and related currently depend on pthread.
+ '../include/utils/SkCondVar.h',
+ '../include/utils/SkCountdown.h',
+ '../include/utils/SkRunnable.h',
+ '../include/utils/SkThreadPool.h',
+ '../src/utils/SkCondVar.cpp',
+ '../src/utils/SkCountdown.cpp',
+ '../src/utils/SkThreadPool.cpp',
],
},{ #else if 'skia_os != "win"'
'include_dirs!': [
diff --git a/include/utils/SkCondVar.h b/include/utils/SkCondVar.h
new file mode 100644
index 0000000..d2539e4
--- /dev/null
+++ b/include/utils/SkCondVar.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkCondVar_DEFINED
+#define SkCondVar_DEFINED
+
+#include <pthread.h>
+
+class SkCondVar {
+public:
+ SkCondVar();
+ ~SkCondVar();
+
+ void lock();
+ void unlock();
+
+ /**
+ * Pause the calling thread. Will be awoken when signal() is called.
+ * Must be called while lock() is held (but gives it up while waiting).
+ */
+ void wait();
+
+ /**
+ * Wake one thread waiting on this condition. Must be called while lock()
+ * is held.
+ */
+ void signal();
+
+ /**
+ * Wake all threads waiting on this condition. Must be called while lock()
+ * is held.
+ */
+ void broadcast();
+
+private:
+ // FIXME: Make this independent of pthreads.
+ pthread_mutex_t fMutex;
+ pthread_cond_t fCond;
+};
+
+#endif
diff --git a/include/utils/SkCountdown.h b/include/utils/SkCountdown.h
new file mode 100644
index 0000000..6bcec7d
--- /dev/null
+++ b/include/utils/SkCountdown.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkCountdown_DEFINED
+#define SkCountdown_DEFINED
+
+#include "SkCondVar.h"
+#include "SkRunnable.h"
+#include "SkTypes.h"
+
+class SkCountdown : public SkRunnable {
+public:
+ explicit SkCountdown(int32_t count);
+
+ /**
+ * Resets the countdown to the count provided.
+ */
+ void reset(int32_t count);
+
+ virtual void run() SK_OVERRIDE;
+
+ /**
+ * Blocks until run() has been called count times.
+ */
+ void wait();
+
+private:
+ SkCondVar fReady;
+ int32_t fCount;
+};
+
+#endif
diff --git a/include/utils/SkRunnable.h b/include/utils/SkRunnable.h
new file mode 100644
index 0000000..c7bedcc
--- /dev/null
+++ b/include/utils/SkRunnable.h
@@ -0,0 +1,16 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkRunnable_DEFINED
+#define SkRunnable_DEFINED
+
+class SkRunnable {
+public:
+ virtual void run() = 0;
+};
+
+#endif
diff --git a/include/utils/SkThreadPool.h b/include/utils/SkThreadPool.h
new file mode 100644
index 0000000..a96f87b
--- /dev/null
+++ b/include/utils/SkThreadPool.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkThreadPool_DEFINED
+#define SkThreadPool_DEFINED
+
+#include "SkCondVar.h"
+#include "SkTDArray.h"
+#include "SkTDLinkedList.h"
+
+class SkRunnable;
+class SkThread;
+
+class SkThreadPool {
+
+public:
+ /**
+ * Create a threadpool with exactly count (>=0) threads.
+ */
+ explicit SkThreadPool(int count);
+ ~SkThreadPool();
+
+ /**
+ * Queues up an SkRunnable to run when a thread is available, or immediately if
+ * count is 0. NULL is a safe no-op. Does not take ownership.
+ */
+ void add(SkRunnable*);
+
+ private:
+ struct LinkedRunnable {
+ // Unowned pointer.
+ SkRunnable* fRunnable;
+
+ private:
+ SK_DEFINE_DLINKEDLIST_INTERFACE(LinkedRunnable)
+ };
+
+ SkTDLinkedList<LinkedRunnable> fQueue;
+ SkCondVar fReady;
+ SkTDArray<SkThread*> fThreads;
+ bool fDone;
+
+ static void Loop(void*); // Static because we pass in this.
+};
+
+#endif
diff --git a/src/utils/SkCondVar.cpp b/src/utils/SkCondVar.cpp
new file mode 100644
index 0000000..8cbab58
--- /dev/null
+++ b/src/utils/SkCondVar.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCondVar.h"
+
+SkCondVar::SkCondVar() {
+ pthread_mutex_init(&fMutex, NULL /* default mutex attr */);
+ pthread_cond_init(&fCond, NULL /* default cond attr */);
+}
+
+SkCondVar::~SkCondVar() {
+ pthread_mutex_destroy(&fMutex);
+ pthread_cond_destroy(&fCond);
+}
+
+void SkCondVar::lock() {
+ pthread_mutex_lock(&fMutex);
+}
+
+void SkCondVar::unlock() {
+ pthread_mutex_unlock(&fMutex);
+}
+
+void SkCondVar::wait() {
+ pthread_cond_wait(&fCond, &fMutex);
+}
+
+void SkCondVar::signal() {
+ pthread_cond_signal(&fCond);
+}
+
+void SkCondVar::broadcast() {
+ pthread_cond_broadcast(&fCond);
+}
diff --git a/src/utils/SkCountdown.cpp b/src/utils/SkCountdown.cpp
new file mode 100644
index 0000000..5b476cc
--- /dev/null
+++ b/src/utils/SkCountdown.cpp
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCountdown.h"
+#include "SkThread.h"
+
+SkCountdown::SkCountdown(int32_t count)
+: fCount(count) {}
+
+void SkCountdown::reset(int32_t count) {
+ fCount = count;
+}
+
+void SkCountdown::run() {
+ if (sk_atomic_dec(&fCount) == 1) {
+ fReady.lock();
+ fReady.signal();
+ fReady.unlock();
+ }
+}
+
+void SkCountdown::wait() {
+ fReady.lock();
+ while (fCount > 0) {
+ fReady.wait();
+ }
+ fReady.unlock();
+}
+
diff --git a/src/utils/SkThreadPool.cpp b/src/utils/SkThreadPool.cpp
new file mode 100644
index 0000000..78cb417
--- /dev/null
+++ b/src/utils/SkThreadPool.cpp
@@ -0,0 +1,88 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkThreadPool.h"
+#include "SkRunnable.h"
+#include "SkThreadUtils.h"
+
+SkThreadPool::SkThreadPool(const int count)
+: fDone(false) {
+ // Create count threads, all running SkThreadPool::Loop.
+ for (int i = 0; i < count; i++) {
+ SkThread* thread = SkNEW_ARGS(SkThread, (&SkThreadPool::Loop, this));
+ *fThreads.append() = thread;
+ thread->start();
+ }
+}
+
+SkThreadPool::~SkThreadPool() {
+ fDone = true;
+ fReady.lock();
+ fReady.broadcast();
+ fReady.unlock();
+
+ // Wait for all threads to stop.
+ for (int i = 0; i < fThreads.count(); i++) {
+ fThreads[i]->join();
+ SkDELETE(fThreads[i]);
+ }
+}
+
+/*static*/ void SkThreadPool::Loop(void* arg) {
+ // The SkThreadPool passes itself as arg to each thread as they're created.
+ SkThreadPool* pool = static_cast<SkThreadPool*>(arg);
+
+ while (true) {
+ // We have to be holding the lock to read the queue and to call wait.
+ pool->fReady.lock();
+ while(pool->fQueue.isEmpty()) {
+ // Is it time to die?
+ if (pool->fDone) {
+ pool->fReady.unlock();
+ return;
+ }
+ // wait yields the lock while waiting, but will have it again when awoken.
+ pool->fReady.wait();
+ }
+ // We've got the lock back here, no matter if we ran wait or not.
+
+ // The queue is not empty, so we have something to run. Claim it.
+ LinkedRunnable* r = pool->fQueue.tail();
+
+ pool->fQueue.remove(r);
+
+ // Having claimed our SkRunnable, we now give up the lock while we run it.
+ // Otherwise, we'd only ever do work on one thread at a time, which rather
+ // defeats the point of this code.
+ pool->fReady.unlock();
+
+ // OK, now really do the work.
+ r->fRunnable->run();
+ SkDELETE(r);
+ }
+
+ SkASSERT(false); // Unreachable. The only exit happens when pool->fDone.
+}
+
+void SkThreadPool::add(SkRunnable* r) {
+ if (NULL == r) {
+ return;
+ }
+
+ // If we don't have any threads, obligingly just run the thing now.
+ if (fThreads.isEmpty()) {
+ return r->run();
+ }
+
+ // We have some threads. Queue it up!
+ fReady.lock();
+ LinkedRunnable* linkedRunnable = SkNEW(LinkedRunnable);
+ linkedRunnable->fRunnable = r;
+ fQueue.addToHead(linkedRunnable);
+ fReady.signal();
+ fReady.unlock();
+}