Make mojo_system static and mojo_system_impl a component, never use both

mojo/system/core.h

+// Copyright 2013 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 MOJO_SYSTEM_CORE_H_
+#define MOJO_SYSTEM_CORE_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "mojo/system/handle_table.h"
+#include "mojo/system/mapping_table.h"
+#include "mojo/system/system_impl_export.h"
+
+namespace mojo {
+namespace system {
+
+class Dispatcher;
+
+// |Core| is an object that implements the Mojo system calls. All public methods
+// are thread-safe.
+class MOJO_SYSTEM_IMPL_EXPORT Core {
+ public:
+  // These methods are only to be used by via the embedder API.
+  Core();
+  virtual ~Core();
+  MojoHandle AddDispatcher(const scoped_refptr<Dispatcher>& dispatcher);
+
+  // System calls implementation.
+  MojoTimeTicks GetTimeTicksNow();
+  MojoResult Close(MojoHandle handle);
+  MojoResult Wait(MojoHandle handle,
+                  MojoWaitFlags flags,
+                  MojoDeadline deadline);
+  MojoResult WaitMany(const MojoHandle* handles,
+                      const MojoWaitFlags* flags,
+                      uint32_t num_handles,
+                      MojoDeadline deadline);
+  MojoResult CreateMessagePipe(
+      MojoHandle* message_pipe_handle0,
+      MojoHandle* message_pipe_handle1);
+  MojoResult WriteMessage(MojoHandle message_pipe_handle,
+                          const void* bytes,
+                          uint32_t num_bytes,
+                          const MojoHandle* handles,
+                          uint32_t num_handles,
+                          MojoWriteMessageFlags flags);
+  MojoResult ReadMessage(MojoHandle message_pipe_handle,
+                         void* bytes,
+                         uint32_t* num_bytes,
+                         MojoHandle* handles,
+                         uint32_t* num_handles,
+                         MojoReadMessageFlags flags);
+  MojoResult CreateDataPipe(
+      const MojoCreateDataPipeOptions* options,
+      MojoHandle* data_pipe_producer_handle,
+      MojoHandle* data_pipe_consumer_handle);
+  MojoResult WriteData(MojoHandle data_pipe_producer_handle,
+                       const void* elements,
+                       uint32_t* num_bytes,
+                       MojoWriteDataFlags flags);
+  MojoResult BeginWriteData(MojoHandle data_pipe_producer_handle,
+                            void** buffer,
+                            uint32_t* buffer_num_bytes,
+                            MojoWriteDataFlags flags);
+  MojoResult EndWriteData(MojoHandle data_pipe_producer_handle,
+                          uint32_t num_bytes_written);
+  MojoResult ReadData(MojoHandle data_pipe_consumer_handle,
+                      void* elements,
+                      uint32_t* num_bytes,
+                      MojoReadDataFlags flags);
+  MojoResult BeginReadData(MojoHandle data_pipe_consumer_handle,
+                           const void** buffer,
+                           uint32_t* buffer_num_bytes,
+                           MojoReadDataFlags flags);
+  MojoResult EndReadData(MojoHandle data_pipe_consumer_handle,
+                         uint32_t num_bytes_read);
+  MojoResult CreateSharedBuffer(
+      const MojoCreateSharedBufferOptions* options,
+      uint64_t num_bytes,
+      MojoHandle* shared_buffer_handle);
+  MojoResult DuplicateBufferHandle(
+      MojoHandle buffer_handle,
+      const MojoDuplicateBufferHandleOptions* options,
+      MojoHandle* new_buffer_handle);
+  MojoResult MapBuffer(MojoHandle buffer_handle,
+                       uint64_t offset,
+                       uint64_t num_bytes,
+                       void** buffer,
+                       MojoMapBufferFlags flags);
+  MojoResult UnmapBuffer(void* buffer);
+
+ private:
+  friend bool internal::ShutdownCheckNoLeaks(Core*);
+  // The |busy| member is used only to deal with functions (in particular
+  // |WriteMessage()|) that want to hold on to a dispatcher and later remove it
+  // from the handle table, without holding on to the handle table lock.
+  //
+  // For example, if |WriteMessage()| is called with a handle to be sent, (under
+  // the handle table lock) it must first check that that handle is not busy (if
+  // it is busy, then it fails with |MOJO_RESULT_BUSY|) and then marks it as
+  // busy. To avoid deadlock, it should also try to acquire the locks for all
+  // the dispatchers for the handles that it is sending (and fail with
+  // |MOJO_RESULT_BUSY| if the attempt fails). At this point, it can release the
+  // handle table lock.
+  //
+  // If |Close()| is simultaneously called on that handle, it too checks if the
+  // handle is marked busy. If it is, it fails (with |MOJO_RESULT_BUSY|). This
+  // prevents |WriteMessage()| from sending a handle that has been closed (or
+  // learning about this too late).
+  struct HandleTableEntry {
+    HandleTableEntry();
+    explicit HandleTableEntry(const scoped_refptr<Dispatcher>& dispatcher);
+    ~HandleTableEntry();
+
+    scoped_refptr<Dispatcher> dispatcher;
+    bool busy;
+  };
+  typedef base::hash_map<MojoHandle, HandleTableEntry> HandleTableMap;
+
+  // Looks up the dispatcher for the given handle. Returns null if the handle is
+  // invalid.
+  scoped_refptr<Dispatcher> GetDispatcher(MojoHandle handle);
+
+  // Internal implementation of |Wait()| and |WaitMany()|; doesn't do basic
+  // validation of arguments.
+  MojoResult WaitManyInternal(const MojoHandle* handles,
+                              const MojoWaitFlags* flags,
+                              uint32_t num_handles,
+                              MojoDeadline deadline);
+
+  // ---------------------------------------------------------------------------
+
+  // TODO(vtl): |handle_table_lock_| should be a reader-writer lock (if only we
+  // had them).
+  base::Lock handle_table_lock_;  // Protects |handle_table_|.
+  HandleTable handle_table_;
+
+  base::Lock mapping_table_lock_;  // Protects |mapping_table_|.
+  MappingTable mapping_table_;
+
+  // ---------------------------------------------------------------------------
+
+  DISALLOW_COPY_AND_ASSIGN(Core);
+};
+
+}  // namespace system
+}  // namespace mojo
+
+#endif  // MOJO_SYSTEM_CORE_H_