Add m-esr52 at 52.6.0

1 files changed, 384 insertions, 0 deletions

diff --git a/security/sandbox/chromium/base/threading/sequenced_worker_pool.h b/security/sandbox/chromium/base/threading/sequenced_worker_pool.h
new file mode 100644
index 000000000..ba0e44421
--- /dev/null
+++ b/security/sandbox/chromium/base/threading/sequenced_worker_pool.h
@@ -0,0 +1,384 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_SEQUENCED_WORKER_POOL_H_
+#define BASE_THREADING_SEQUENCED_WORKER_POOL_H_
+
+#include <stddef.h>
+
+#include <cstddef>
+#include <string>
+
+#include "base/base_export.h"
+#include "base/callback_forward.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_runner.h"
+
+namespace tracked_objects {
+class Location;
+}  // namespace tracked_objects
+
+namespace base {
+
+class SingleThreadTaskRunner;
+
+template <class T> class DeleteHelper;
+
+class SequencedTaskRunner;
+
+// A worker thread pool that enforces ordering between sets of tasks. It also
+// allows you to specify what should happen to your tasks on shutdown.
+//
+// To enforce ordering, get a unique sequence token from the pool and post all
+// tasks you want to order with the token. All tasks with the same token are
+// guaranteed to execute serially, though not necessarily on the same thread.
+// This means that:
+//
+//   - No two tasks with the same token will run at the same time.
+//
+//   - Given two tasks T1 and T2 with the same token such that T2 will
+//     run after T1, then T2 will start after T1 is destroyed.
+//
+//   - If T2 will run after T1, then all memory changes in T1 and T1's
+//     destruction will be visible to T2.
+//
+// Example:
+//   SequencedWorkerPool::SequenceToken token =
+//       SequencedWorkerPool::GetSequenceToken();
+//   pool.PostSequencedWorkerTask(token, SequencedWorkerPool::SKIP_ON_SHUTDOWN,
+//                                FROM_HERE, base::Bind(...));
+//   pool.PostSequencedWorkerTask(token, SequencedWorkerPool::SKIP_ON_SHUTDOWN,
+//                                FROM_HERE, base::Bind(...));
+//
+// You can make named sequence tokens to make it easier to share a token
+// across different components.
+//
+// You can also post tasks to the pool without ordering using PostWorkerTask.
+// These will be executed in an unspecified order. The order of execution
+// between tasks with different sequence tokens is also unspecified.
+//
+// This class may be leaked on shutdown to facilitate fast shutdown. The
+// expected usage, however, is to call Shutdown(), which correctly accounts
+// for CONTINUE_ON_SHUTDOWN behavior and is required for BLOCK_SHUTDOWN
+// behavior.
+//
+// Implementation note: This does not use a base::WorkerPool since that does
+// not enforce shutdown semantics or allow us to specify how many worker
+// threads to run. For the typical use case of random background work, we don't
+// necessarily want to be super aggressive about creating threads.
+//
+// Note that SequencedWorkerPool is RefCountedThreadSafe (inherited
+// from TaskRunner).
+//
+// Test-only code should wrap this in a base::SequencedWorkerPoolOwner to avoid
+// memory leaks. See http://crbug.com/273800
+class BASE_EXPORT SequencedWorkerPool : public TaskRunner {
+ public:
+  // Defines what should happen to a task posted to the worker pool on
+  // shutdown.
+  enum WorkerShutdown {
+    // Tasks posted with this mode which have not run at shutdown will be
+    // deleted rather than run, and any tasks with this mode running at
+    // shutdown will be ignored (the worker thread will not be joined).
+    //
+    // This option provides a nice way to post stuff you don't want blocking
+    // shutdown. For example, you might be doing a slow DNS lookup and if it's
+    // blocked on the OS, you may not want to stop shutdown, since the result
+    // doesn't really matter at that point.
+    //
+    // However, you need to be very careful what you do in your callback when
+    // you use this option. Since the thread will continue to run until the OS
+    // terminates the process, the app can be in the process of tearing down
+    // when you're running. This means any singletons or global objects you
+    // use may suddenly become invalid out from under you. For this reason,
+    // it's best to use this only for slow but simple operations like the DNS
+    // example.
+    CONTINUE_ON_SHUTDOWN,
+
+    // Tasks posted with this mode that have not started executing at
+    // shutdown will be deleted rather than executed. However, any tasks that
+    // have already begun executing when shutdown is called will be allowed
+    // to continue, and will block shutdown until completion.
+    //
+    // Note: Because Shutdown() may block while these tasks are executing,
+    // care must be taken to ensure that they do not block on the thread that
+    // called Shutdown(), as this may lead to deadlock.
+    SKIP_ON_SHUTDOWN,
+
+    // Tasks posted with this mode will block shutdown until they're
+    // executed. Since this can have significant performance implications,
+    // use sparingly.
+    //
+    // Generally, this should be used only for user data, for example, a task
+    // writing a preference file.
+    //
+    // If a task is posted during shutdown, it will not get run since the
+    // workers may already be stopped. In this case, the post operation will
+    // fail (return false) and the task will be deleted.
+    BLOCK_SHUTDOWN,
+  };
+
+  // Opaque identifier that defines sequencing of tasks posted to the worker
+  // pool.
+  class BASE_EXPORT SequenceToken {
+   public:
+    SequenceToken() : id_(0) {}
+    ~SequenceToken() {}
+
+    bool Equals(const SequenceToken& other) const {
+      return id_ == other.id_;
+    }
+
+    // Returns false if current thread is executing an unsequenced task.
+    bool IsValid() const {
+      return id_ != 0;
+    }
+
+    // Returns a string representation of this token. This method should only be
+    // used for debugging.
+    std::string ToString() const;
+
+   private:
+    friend class SequencedWorkerPool;
+
+    explicit SequenceToken(int id) : id_(id) {}
+
+    int id_;
+  };
+
+  // Allows tests to perform certain actions.
+  class TestingObserver {
+   public:
+    virtual ~TestingObserver() {}
+    virtual void OnHasWork() = 0;
+    virtual void WillWaitForShutdown() = 0;
+    virtual void OnDestruct() = 0;
+  };
+
+  // Gets the SequencedToken of the current thread.
+  // If current thread is not a SequencedWorkerPool worker thread or is running
+  // an unsequenced task, returns an invalid SequenceToken.
+  static SequenceToken GetSequenceTokenForCurrentThread();
+
+  // Gets a SequencedTaskRunner for the current thread. If the current thread is
+  // running an unsequenced task, a new SequenceToken will be generated and set,
+  // so that the returned SequencedTaskRunner is guaranteed to run tasks after
+  // the current task has finished running.
+  static scoped_refptr<SequencedTaskRunner>
+  GetSequencedTaskRunnerForCurrentThread();
+
+  // Returns a unique token that can be used to sequence tasks posted to
+  // PostSequencedWorkerTask(). Valid tokens are always nonzero.
+  // TODO(bauerb): Rename this to better differentiate from
+  // GetSequenceTokenForCurrentThread().
+  static SequenceToken GetSequenceToken();
+
+  // Returns the SequencedWorkerPool that owns this thread, or null if the
+  // current thread is not a SequencedWorkerPool worker thread.
+  static scoped_refptr<SequencedWorkerPool> GetWorkerPoolForCurrentThread();
+
+  // When constructing a SequencedWorkerPool, there must be a
+  // ThreadTaskRunnerHandle on the current thread unless you plan to
+  // deliberately leak it.
+
+  // Pass the maximum number of threads (they will be lazily created as needed)
+  // and a prefix for the thread name to aid in debugging.
+  SequencedWorkerPool(size_t max_threads,
+                      const std::string& thread_name_prefix);
+
+  // Like above, but with |observer| for testing.  Does not take ownership of
+  // |observer|.
+  SequencedWorkerPool(size_t max_threads,
+                      const std::string& thread_name_prefix,
+                      TestingObserver* observer);
+
+  // Returns the sequence token associated with the given name. Calling this
+  // function multiple times with the same string will always produce the
+  // same sequence token. If the name has not been used before, a new token
+  // will be created.
+  SequenceToken GetNamedSequenceToken(const std::string& name);
+
+  // Returns a SequencedTaskRunner wrapper which posts to this
+  // SequencedWorkerPool using the given sequence token. Tasks with nonzero
+  // delay are posted with SKIP_ON_SHUTDOWN behavior and tasks with zero delay
+  // are posted with BLOCK_SHUTDOWN behavior.
+  scoped_refptr<SequencedTaskRunner> GetSequencedTaskRunner(
+      SequenceToken token);
+
+  // Returns a SequencedTaskRunner wrapper which posts to this
+  // SequencedWorkerPool using the given sequence token. Tasks with nonzero
+  // delay are posted with SKIP_ON_SHUTDOWN behavior and tasks with zero delay
+  // are posted with the given shutdown behavior.
+  scoped_refptr<SequencedTaskRunner> GetSequencedTaskRunnerWithShutdownBehavior(
+      SequenceToken token,
+      WorkerShutdown shutdown_behavior);
+
+  // Returns a TaskRunner wrapper which posts to this SequencedWorkerPool using
+  // the given shutdown behavior. Tasks with nonzero delay are posted with
+  // SKIP_ON_SHUTDOWN behavior and tasks with zero delay are posted with the
+  // given shutdown behavior.
+  scoped_refptr<TaskRunner> GetTaskRunnerWithShutdownBehavior(
+      WorkerShutdown shutdown_behavior);
+
+  // Posts the given task for execution in the worker pool. Tasks posted with
+  // this function will execute in an unspecified order on a background thread.
+  // Returns true if the task was posted. If your tasks have ordering
+  // requirements, see PostSequencedWorkerTask().
+  //
+  // This class will attempt to delete tasks that aren't run
+  // (non-block-shutdown semantics) but can't guarantee that this happens. If
+  // all worker threads are busy running CONTINUE_ON_SHUTDOWN tasks, there
+  // will be no workers available to delete these tasks. And there may be
+  // tasks with the same sequence token behind those CONTINUE_ON_SHUTDOWN
+  // tasks. Deleting those tasks before the previous one has completed could
+  // cause nondeterministic crashes because the task could be keeping some
+  // objects alive which do work in their destructor, which could voilate the
+  // assumptions of the running task.
+  //
+  // The task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  //
+  // Returns true if the task was posted successfully. This may fail during
+  // shutdown regardless of the specified ShutdownBehavior.
+  bool PostWorkerTask(const tracked_objects::Location& from_here,
+                      const Closure& task);
+
+  // Same as PostWorkerTask but allows a delay to be specified (although doing
+  // so changes the shutdown behavior). The task will be run after the given
+  // delay has elapsed.
+  //
+  // If the delay is nonzero, the task won't be guaranteed to run to completion
+  // before shutdown (SKIP_ON_SHUTDOWN semantics) to avoid shutdown hangs.
+  // If the delay is zero, this behaves exactly like PostWorkerTask, i.e. the
+  // task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  bool PostDelayedWorkerTask(const tracked_objects::Location& from_here,
+                             const Closure& task,
+                             TimeDelta delay);
+
+  // Same as PostWorkerTask but allows specification of the shutdown behavior.
+  bool PostWorkerTaskWithShutdownBehavior(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      WorkerShutdown shutdown_behavior);
+
+  // Like PostWorkerTask above, but provides sequencing semantics. This means
+  // that tasks posted with the same sequence token (see GetSequenceToken())
+  // are guaranteed to execute in order. This is useful in cases where you're
+  // doing operations that may depend on previous ones, like appending to a
+  // file.
+  //
+  // The task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  //
+  // Returns true if the task was posted successfully. This may fail during
+  // shutdown regardless of the specified ShutdownBehavior.
+  bool PostSequencedWorkerTask(SequenceToken sequence_token,
+                               const tracked_objects::Location& from_here,
+                               const Closure& task);
+
+  // Like PostSequencedWorkerTask above, but allows you to specify a named
+  // token, which saves an extra call to GetNamedSequenceToken.
+  bool PostNamedSequencedWorkerTask(const std::string& token_name,
+                                    const tracked_objects::Location& from_here,
+                                    const Closure& task);
+
+  // Same as PostSequencedWorkerTask but allows a delay to be specified
+  // (although doing so changes the shutdown behavior). The task will be run
+  // after the given delay has elapsed.
+  //
+  // If the delay is nonzero, the task won't be guaranteed to run to completion
+  // before shutdown (SKIP_ON_SHUTDOWN semantics) to avoid shutdown hangs.
+  // If the delay is zero, this behaves exactly like PostSequencedWorkerTask,
+  // i.e. the task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  bool PostDelayedSequencedWorkerTask(
+      SequenceToken sequence_token,
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      TimeDelta delay);
+
+  // Same as PostSequencedWorkerTask but allows specification of the shutdown
+  // behavior.
+  bool PostSequencedWorkerTaskWithShutdownBehavior(
+      SequenceToken sequence_token,
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      WorkerShutdown shutdown_behavior);
+
+  // TaskRunner implementation. Forwards to PostDelayedWorkerTask().
+  bool PostDelayedTask(const tracked_objects::Location& from_here,
+                       const Closure& task,
+                       TimeDelta delay) override;
+  bool RunsTasksOnCurrentThread() const override;
+
+  // Returns true if the current thread is processing a task with the given
+  // sequence_token.
+  bool IsRunningSequenceOnCurrentThread(SequenceToken sequence_token) const;
+
+  // Returns true if any thread is currently processing a task with the given
+  // sequence token. Should only be called with a valid sequence token.
+  bool IsRunningSequence(SequenceToken sequence_token) const;
+
+  // Blocks until all pending tasks are complete. This should only be called in
+  // unit tests when you want to validate something that should have happened.
+  // This will not flush delayed tasks; delayed tasks get deleted.
+  //
+  // Note that calling this will not prevent other threads from posting work to
+  // the queue while the calling thread is waiting on Flush(). In this case,
+  // Flush will return only when there's no more work in the queue. Normally,
+  // this doesn't come up since in a test, all the work is being posted from
+  // the main thread.
+  void FlushForTesting();
+
+  // Spuriously signal that there is work to be done.
+  void SignalHasWorkForTesting();
+
+  // Implements the worker pool shutdown. This should be called during app
+  // shutdown, and will discard/join with appropriate tasks before returning.
+  // After this call, subsequent calls to post tasks will fail.
+  //
+  // Must be called from the same thread this object was constructed on.
+  void Shutdown() { Shutdown(0); }
+
+  // A variant that allows an arbitrary number of new blocking tasks to be
+  // posted during shutdown. The tasks cannot be posted within the execution
+  // context of tasks whose shutdown behavior is not BLOCKING_SHUTDOWN. Once
+  // the limit is reached, subsequent calls to post task fail in all cases.
+  // Must be called from the same thread this object was constructed on.
+  void Shutdown(int max_new_blocking_tasks_after_shutdown);
+
+  // Check if Shutdown was called for given threading pool. This method is used
+  // for aborting time consuming operation to avoid blocking shutdown.
+  //
+  // Can be called from any thread.
+  bool IsShutdownInProgress();
+
+ protected:
+  ~SequencedWorkerPool() override;
+
+  void OnDestruct() const override;
+
+ private:
+  friend class RefCountedThreadSafe<SequencedWorkerPool>;
+  friend class DeleteHelper<SequencedWorkerPool>;
+
+  class Inner;
+  class Worker;
+
+  const scoped_refptr<SingleThreadTaskRunner> constructor_task_runner_;
+
+  // Avoid pulling in too many headers by putting (almost) everything
+  // into |inner_|.
+  const scoped_ptr<Inner> inner_;
+
+  DISALLOW_COPY_AND_ASSIGN(SequencedWorkerPool);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_SEQUENCED_WORKER_POOL_H_