1 files changed, 99 insertions, 0 deletions
diff --git a/dom/media/systemservices/ShmemPool.cpp b/dom/media/systemservices/ShmemPool.cpp
new file mode 100644
index 0000000000..c39ed5e790
--- /dev/null
+++ b/dom/media/systemservices/ShmemPool.cpp
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et ft=cpp : */
+/* 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/. */
+
+#include "mozilla/ShmemPool.h"
+
+#include <utility>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Logging.h"
+
+mozilla::LazyLogModule sShmemPoolLog("ShmemPool");
+
+#define SHMEMPOOL_LOG_VERBOSE(args) \
+  MOZ_LOG(sShmemPoolLog, mozilla::LogLevel::Verbose, args)
+
+namespace mozilla {
+
+ShmemPool::ShmemPool(size_t aPoolSize, PoolType aPoolType)
+    : mPoolType(aPoolType),
+      mMutex("mozilla::ShmemPool"),
+      mPoolFree(aPoolSize),
+      mErrorLogged(false)
+#ifdef DEBUG
+      ,
+      mMaxPoolUse(0)
+#endif
+{
+  mShmemPool.SetLength(aPoolSize);
+}
+
+mozilla::ShmemBuffer ShmemPool::GetIfAvailable(size_t aSize) {
+  MutexAutoLock lock(mMutex);
+
+  // Pool is empty, don't block caller.
+  if (mPoolFree == 0) {
+    if (!mErrorLogged) {
+      // log "out of pool" once as error to avoid log spam
+      mErrorLogged = true;
+      SHMEMPOOL_LOG_ERROR(
+          ("ShmemPool is empty, future occurrences "
+           "will be logged as warnings"));
+    } else {
+      SHMEMPOOL_LOG_WARN(("ShmemPool is empty"));
+    }
+    // This isn't initialized, so will be understood as an error.
+    return ShmemBuffer();
+  }
+
+  ShmemBuffer& res = mShmemPool[mPoolFree - 1];
+
+  if (!res.mInitialized) {
+    SHMEMPOOL_LOG(("No free preallocated Shmem"));
+    return ShmemBuffer();
+  }
+
+  MOZ_ASSERT(res.mShmem.IsWritable(), "Pool in Shmem is not writable?");
+
+  if (res.mShmem.Size<uint8_t>() < aSize) {
+    SHMEMPOOL_LOG(("Free Shmem but not of the right size"));
+    return ShmemBuffer();
+  }
+
+  mPoolFree--;
+#ifdef DEBUG
+  size_t poolUse = mShmemPool.Length() - mPoolFree;
+  if (poolUse > mMaxPoolUse) {
+    mMaxPoolUse = poolUse;
+    SHMEMPOOL_LOG(
+        ("Maximum ShmemPool use increased: %zu buffers", mMaxPoolUse));
+  }
+#endif
+  return std::move(res);
+}
+
+void ShmemPool::Put(ShmemBuffer&& aShmem) {
+  MutexAutoLock lock(mMutex);
+  MOZ_ASSERT(mPoolFree < mShmemPool.Length());
+  mShmemPool[mPoolFree] = std::move(aShmem);
+  mPoolFree++;
+#ifdef DEBUG
+  size_t poolUse = mShmemPool.Length() - mPoolFree;
+  if (poolUse > 0) {
+    SHMEMPOOL_LOG_VERBOSE(("ShmemPool usage reduced to %zu buffers", poolUse));
+  }
+#endif
+}
+
+ShmemPool::~ShmemPool() {
+#ifdef DEBUG
+  for (size_t i = 0; i < mShmemPool.Length(); i++) {
+    MOZ_ASSERT(!mShmemPool[i].Valid());
+  }
+#endif
+}
+
+}  // namespace mozilla