1 files changed, 149 insertions, 0 deletions
diff --git a/netwerk/cache2/CacheIOThread.h b/netwerk/cache2/CacheIOThread.h
new file mode 100644
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+++ b/netwerk/cache2/CacheIOThread.h
@@ -0,0 +1,149 @@
+/* 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/. */
+
+#ifndef CacheIOThread__h__
+#define CacheIOThread__h__
+
+#include "nsIThreadInternal.h"
+#include "nsISupportsImpl.h"
+#include "prthread.h"
+#include "nsTArray.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/UniquePtr.h"
+
+class nsIRunnable;
+
+namespace mozilla {
+namespace net {
+
+namespace detail {
+// A class keeping platform specific information needed to
+// cancel any long blocking synchronous IO.  Must be predeclared here
+// since including windows.h breaks stuff with number of macro definition
+// conflicts.
+class NativeThreadHandle;
+}  // namespace detail
+
+class CacheIOThread final : public nsIThreadObserver {
+  virtual ~CacheIOThread();
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSITHREADOBSERVER
+
+  CacheIOThread();
+
+  using EventQueue = nsTArray<nsCOMPtr<nsIRunnable>>;
+
+  enum ELevel : uint32_t {
+    OPEN_PRIORITY,
+    READ_PRIORITY,
+    MANAGEMENT,  // Doesn't do any actual I/O
+    OPEN,
+    READ,
+    WRITE_PRIORITY,
+    WRITE,
+    INDEX,
+    EVICT,
+    LAST_LEVEL,
+
+    // This is actually executed as the first level, but we want this enum
+    // value merely as an indicator while other values are used as indexes
+    // to the queue array.  Hence put at end and not as the first.
+    XPCOM_LEVEL
+  };
+
+  nsresult Init();
+  nsresult Dispatch(nsIRunnable* aRunnable, uint32_t aLevel);
+  nsresult Dispatch(already_AddRefed<nsIRunnable>, uint32_t aLevel);
+  // Makes sure that any previously posted event to OPEN or OPEN_PRIORITY
+  // levels (such as file opennings and dooms) are executed before aRunnable
+  // that is intended to evict stuff from the cache.
+  nsresult DispatchAfterPendingOpens(nsIRunnable* aRunnable);
+  bool IsCurrentThread();
+
+  uint32_t QueueSize(bool highPriority);
+
+  uint32_t EventCounter() const { return mEventCounter; }
+
+  /**
+   * Callable only on this thread, checks if there is an event waiting in
+   * the event queue with a higher execution priority.  If so, the result
+   * is true and the current event handler should break it's work and return
+   * from Run() method immediately.  The event handler will be rerun again
+   * when all more priority events are processed.  Events pending after this
+   * handler (i.e. the one that called YieldAndRerun()) will not execute sooner
+   * then this handler is executed w/o a call to YieldAndRerun().
+   */
+  static bool YieldAndRerun() { return sSelf ? sSelf->YieldInternal() : false; }
+
+  void Shutdown();
+  // This method checks if there is a long blocking IO on the
+  // IO thread and tries to cancel it.  It waits maximum of
+  // two seconds.
+  void CancelBlockingIO();
+  already_AddRefed<nsIEventTarget> Target();
+
+  // A stack class used to annotate running interruptable I/O event
+  class Cancelable {
+    bool mCancelable;
+
+   public:
+    explicit Cancelable(bool aCancelable);
+    ~Cancelable();
+  };
+
+  // Memory reporting
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
+
+ private:
+  static void ThreadFunc(void* aClosure);
+  void ThreadFunc();
+  void LoopOneLevel(uint32_t aLevel) MOZ_REQUIRES(mMonitor);
+  bool EventsPending(uint32_t aLastLevel = LAST_LEVEL);
+  nsresult DispatchInternal(already_AddRefed<nsIRunnable> aRunnable,
+                            uint32_t aLevel);
+  bool YieldInternal();
+
+  static CacheIOThread* sSelf;
+
+  mozilla::Monitor mMonitor{"CacheIOThread"};
+  PRThread* mThread{nullptr};
+  // Only set in Init(), before the thread is started, which reads it but never
+  // writes
+  UniquePtr<detail::NativeThreadHandle> mNativeThreadHandle;
+  Atomic<nsIThread*> mXPCOMThread{nullptr};
+  Atomic<uint32_t, Relaxed> mLowestLevelWaiting{LAST_LEVEL};
+  uint32_t mCurrentlyExecutingLevel{0};  // only accessed on CacheIO Thread
+
+  // Keeps the length of the each event queue, since LoopOneLevel moves all
+  // events into a local array.
+  Atomic<int32_t> mQueueLength[LAST_LEVEL];
+
+  EventQueue mEventQueue[LAST_LEVEL] MOZ_GUARDED_BY(mMonitor);
+  // Raised when nsIEventTarget.Dispatch() is called on this thread
+  Atomic<bool, Relaxed> mHasXPCOMEvents{false};
+  // See YieldAndRerun() above
+  bool mRerunCurrentEvent{false};  // Only accessed on the cache thread
+  // Signal to process all pending events and then shutdown
+  // Synchronized by mMonitor
+  bool mShutdown MOZ_GUARDED_BY(mMonitor){false};
+  // If > 0 there is currently an I/O operation on the thread that
+  // can be canceled when after shutdown, see the Shutdown() method
+  // for usage. Made a counter to allow nesting of the Cancelable class.
+  Atomic<uint32_t, Relaxed> mIOCancelableEvents{0};
+  // Event counter that increases with every event processed.
+  Atomic<uint32_t, Relaxed> mEventCounter{0};
+#ifdef DEBUG
+  bool mInsideLoop MOZ_GUARDED_BY(mMonitor){true};
+#endif
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif