Revert "Move mojo edk into mojo/edk"

mojo/edk/system/dispatcher.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_EDK_SYSTEM_DISPATCHER_H_
-#define MOJO_EDK_SYSTEM_DISPATCHER_H_
-
-#include <stddef.h>
-#include <stdint.h>
-
-#include <vector>
-
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/synchronization/lock.h"
-#include "mojo/edk/embedder/platform_handle.h"
-#include "mojo/edk/embedder/platform_handle_vector.h"
-#include "mojo/edk/system/handle_signals_state.h"
-#include "mojo/edk/system/memory.h"
-#include "mojo/edk/system/system_impl_export.h"
-#include "mojo/public/c/system/buffer.h"
-#include "mojo/public/c/system/data_pipe.h"
-#include "mojo/public/c/system/message_pipe.h"
-#include "mojo/public/c/system/types.h"
-
-namespace mojo {
-
-namespace embedder {
-class PlatformSharedBufferMapping;
-}
-
-namespace system {
-
-class Channel;
-class Core;
-class Dispatcher;
-class DispatcherTransport;
-class HandleTable;
-class LocalMessagePipeEndpoint;
-class ProxyMessagePipeEndpoint;
-class TransportData;
-class Waiter;
-
-typedef std::vector<scoped_refptr<Dispatcher>> DispatcherVector;
-
-namespace test {
-
-// Test helper. We need to declare it here so we can friend it.
-MOJO_SYSTEM_IMPL_EXPORT DispatcherTransport
-    DispatcherTryStartTransport(Dispatcher* dispatcher);
-
-}  // namespace test
-
-// A |Dispatcher| implements Mojo primitives that are "attached" to a particular
-// handle. This includes most (all?) primitives except for |MojoWait...()|. This
-// object is thread-safe, with its state being protected by a single lock
-// |lock_|, which is also made available to implementation subclasses (via the
-// |lock()| method).
-class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
-    : public base::RefCountedThreadSafe<Dispatcher> {
- public:
-  enum Type {
-    kTypeUnknown = 0,
-    kTypeMessagePipe,
-    kTypeDataPipeProducer,
-    kTypeDataPipeConsumer,
-    kTypeSharedBuffer,
-
-    // "Private" types (not exposed via the public interface):
-    kTypePlatformHandle = -1
-  };
-  virtual Type GetType() const = 0;
-
-  // These methods implement the various primitives named |Mojo...()|. These
-  // take |lock_| and handle races with |Close()|. Then they call out to
-  // subclasses' |...ImplNoLock()| methods (still under |lock_|), which actually
-  // implement the primitives.
-  // NOTE(vtl): This puts a big lock around each dispatcher (i.e., handle), and
-  // prevents the various |...ImplNoLock()|s from releasing the lock as soon as
-  // possible. If this becomes an issue, we can rethink this.
-  MojoResult Close();
-
-  // |transports| may be non-null if and only if there are handles to be
-  // written; not that |this| must not be in |transports|. On success, all the
-  // dispatchers in |transports| must have been moved to a closed state; on
-  // failure, they should remain in their original state.
-  MojoResult WriteMessage(UserPointer<const void> bytes,
-                          uint32_t num_bytes,
-                          std::vector<DispatcherTransport>* transports,
-                          MojoWriteMessageFlags flags);
-  // |dispatchers| must be non-null but empty, if |num_dispatchers| is non-null
-  // and nonzero. On success, it will be set to the dispatchers to be received
-  // (and assigned handles) as part of the message.
-  MojoResult ReadMessage(UserPointer<void> bytes,
-                         UserPointer<uint32_t> num_bytes,
-                         DispatcherVector* dispatchers,
-                         uint32_t* num_dispatchers,
-                         MojoReadMessageFlags flags);
-  MojoResult WriteData(UserPointer<const void> elements,
-                       UserPointer<uint32_t> elements_num_bytes,
-                       MojoWriteDataFlags flags);
-  MojoResult BeginWriteData(UserPointer<void*> buffer,
-                            UserPointer<uint32_t> buffer_num_bytes,
-                            MojoWriteDataFlags flags);
-  MojoResult EndWriteData(uint32_t num_bytes_written);
-  MojoResult ReadData(UserPointer<void> elements,
-                      UserPointer<uint32_t> num_bytes,
-                      MojoReadDataFlags flags);
-  MojoResult BeginReadData(UserPointer<const void*> buffer,
-                           UserPointer<uint32_t> buffer_num_bytes,
-                           MojoReadDataFlags flags);
-  MojoResult EndReadData(uint32_t num_bytes_read);
-  // |options| may be null. |new_dispatcher| must not be null, but
-  // |*new_dispatcher| should be null (and will contain the dispatcher for the
-  // new handle on success).
-  MojoResult DuplicateBufferHandle(
-      UserPointer<const MojoDuplicateBufferHandleOptions> options,
-      scoped_refptr<Dispatcher>* new_dispatcher);
-  MojoResult MapBuffer(
-      uint64_t offset,
-      uint64_t num_bytes,
-      MojoMapBufferFlags flags,
-      scoped_ptr<embedder::PlatformSharedBufferMapping>* mapping);
-
-  // Gets the current handle signals state. (The default implementation simply
-  // returns a default-constructed |HandleSignalsState|, i.e., no signals
-  // satisfied or satisfiable.) Note: The state is subject to change from other
-  // threads.
-  HandleSignalsState GetHandleSignalsState() const;
-
-  // Adds a waiter to this dispatcher. The waiter will be woken up when this
-  // object changes state to satisfy |signals| with context |context|. It will
-  // also be woken up when it becomes impossible for the object to ever satisfy
-  // |signals| with a suitable error status.
-  //
-  // If |signals_state| is non-null, on *failure* |*signals_state| will be set
-  // to the current handle signals state (on success, it is left untouched).
-  //
-  // Returns:
-  //  - |MOJO_RESULT_OK| if the waiter was added;
-  //  - |MOJO_RESULT_ALREADY_EXISTS| if |signals| is already satisfied;
-  //  - |MOJO_RESULT_INVALID_ARGUMENT| if the dispatcher has been closed; and
-  //  - |MOJO_RESULT_FAILED_PRECONDITION| if it is not (or no longer) possible
-  //    that |signals| will ever be satisfied.
-  MojoResult AddWaiter(Waiter* waiter,
-                       MojoHandleSignals signals,
-                       uint32_t context,
-                       HandleSignalsState* signals_state);
-  // Removes a waiter from this dispatcher. (It is valid to call this multiple
-  // times for the same |waiter| on the same object, so long as |AddWaiter()|
-  // was called at most once.) If |signals_state| is non-null, |*signals_state|
-  // will be set to the current handle signals state.
-  void RemoveWaiter(Waiter* waiter, HandleSignalsState* signals_state);
-
-  // A dispatcher must be put into a special state in order to be sent across a
-  // message pipe. Outside of tests, only |HandleTableAccess| is allowed to do
-  // this, since there are requirements on the handle table (see below).
-  //
-  // In this special state, only a restricted set of operations is allowed.
-  // These are the ones available as |DispatcherTransport| methods. Other
-  // |Dispatcher| methods must not be called until |DispatcherTransport::End()|
-  // has been called.
-  class HandleTableAccess {
-   private:
-    friend class Core;
-    friend class HandleTable;
-    // Tests also need this, to avoid needing |Core|.
-    friend DispatcherTransport test::DispatcherTryStartTransport(Dispatcher*);
-
-    // This must be called under the handle table lock and only if the handle
-    // table entry is not marked busy. The caller must maintain a reference to
-    // |dispatcher| until |DispatcherTransport::End()| is called.
-    static DispatcherTransport TryStartTransport(Dispatcher* dispatcher);
-  };
-
-  // A |TransportData| may serialize dispatchers that are given to it (and which
-  // were previously attached to the |MessageInTransit| that is creating it) to
-  // a given |Channel| and then (probably in a different process) deserialize.
-  // Note that the |MessageInTransit| "owns" (i.e., has the only ref to) these
-  // dispatchers, so there are no locking issues. (There's no lock ordering
-  // issue, and in fact no need to take dispatcher locks at all.)
-  // TODO(vtl): Consider making another wrapper similar to |DispatcherTransport|
-  // (but with an owning, unique reference), and having
-  // |CreateEquivalentDispatcherAndCloseImplNoLock()| return that wrapper (and
-  // |MessageInTransit|, etc. only holding on to such wrappers).
-  class TransportDataAccess {
-   private:
-    friend class TransportData;
-
-    // Serialization API. These functions may only be called on such
-    // dispatchers. (|channel| is the |Channel| to which the dispatcher is to be
-    // serialized.) See the |Dispatcher| methods of the same names for more
-    // details.
-    static void StartSerialize(Dispatcher* dispatcher,
-                               Channel* channel,
-                               size_t* max_size,
-                               size_t* max_platform_handles);
-    static bool EndSerializeAndClose(
-        Dispatcher* dispatcher,
-        Channel* channel,
-        void* destination,
-        size_t* actual_size,
-        embedder::PlatformHandleVector* platform_handles);
-
-    // Deserialization API.
-    // Note: This "clears" (i.e., reset to the invalid handle) any platform
-    // handles that it takes ownership of.
-    static scoped_refptr<Dispatcher> Deserialize(
-        Channel* channel,
-        int32_t type,
-        const void* source,
-        size_t size,
-        embedder::PlatformHandleVector* platform_handles);
-  };
-
- protected:
-  friend class base::RefCountedThreadSafe<Dispatcher>;
-
-  Dispatcher();
-  virtual ~Dispatcher();
-
-  // These are to be overridden by subclasses (if necessary). They are called
-  // exactly once -- first |CancelAllWaitersNoLock()|, then |CloseImplNoLock()|,
-  // when the dispatcher is being closed. They are called under |lock_|.
-  virtual void CancelAllWaitersNoLock();
-  virtual void CloseImplNoLock();
-  virtual scoped_refptr<Dispatcher>
-      CreateEquivalentDispatcherAndCloseImplNoLock() = 0;
-
-  // These are to be overridden by subclasses (if necessary). They are never
-  // called after the dispatcher has been closed. They are called under |lock_|.
-  // See the descriptions of the methods without the "ImplNoLock" for more
-  // information.
-  virtual MojoResult WriteMessageImplNoLock(
-      UserPointer<const void> bytes,
-      uint32_t num_bytes,
-      std::vector<DispatcherTransport>* transports,
-      MojoWriteMessageFlags flags);
-  virtual MojoResult ReadMessageImplNoLock(UserPointer<void> bytes,
-                                           UserPointer<uint32_t> num_bytes,
-                                           DispatcherVector* dispatchers,
-                                           uint32_t* num_dispatchers,
-                                           MojoReadMessageFlags flags);
-  virtual MojoResult WriteDataImplNoLock(UserPointer<const void> elements,
-                                         UserPointer<uint32_t> num_bytes,
-                                         MojoWriteDataFlags flags);
-  virtual MojoResult BeginWriteDataImplNoLock(
-      UserPointer<void*> buffer,
-      UserPointer<uint32_t> buffer_num_bytes,
-      MojoWriteDataFlags flags);
-  virtual MojoResult EndWriteDataImplNoLock(uint32_t num_bytes_written);
-  virtual MojoResult ReadDataImplNoLock(UserPointer<void> elements,
-                                        UserPointer<uint32_t> num_bytes,
-                                        MojoReadDataFlags flags);
-  virtual MojoResult BeginReadDataImplNoLock(
-      UserPointer<const void*> buffer,
-      UserPointer<uint32_t> buffer_num_bytes,
-      MojoReadDataFlags flags);
-  virtual MojoResult EndReadDataImplNoLock(uint32_t num_bytes_read);
-  virtual MojoResult DuplicateBufferHandleImplNoLock(
-      UserPointer<const MojoDuplicateBufferHandleOptions> options,
-      scoped_refptr<Dispatcher>* new_dispatcher);
-  virtual MojoResult MapBufferImplNoLock(
-      uint64_t offset,
-      uint64_t num_bytes,
-      MojoMapBufferFlags flags,
-      scoped_ptr<embedder::PlatformSharedBufferMapping>* mapping);
-  virtual HandleSignalsState GetHandleSignalsStateImplNoLock() const;
-  virtual MojoResult AddWaiterImplNoLock(Waiter* waiter,
-                                         MojoHandleSignals signals,
-                                         uint32_t context,
-                                         HandleSignalsState* signals_state);
-  virtual void RemoveWaiterImplNoLock(Waiter* waiter,
-                                      HandleSignalsState* signals_state);
-
-  // These implement the API used to serialize dispatchers to a |Channel|
-  // (described below). They will only be called on a dispatcher that's attached
-  // to and "owned" by a |MessageInTransit|. See the non-"impl" versions for
-  // more information.
-  //
-  // Note: |StartSerializeImplNoLock()| is actually called with |lock_| NOT
-  // held, since the dispatcher should only be accessible to the calling thread.
-  // On Debug builds, |EndSerializeAndCloseImplNoLock()| is called with |lock_|
-  // held, to satisfy any |lock_.AssertAcquired()| (e.g., in |CloseImplNoLock()|
-  // -- and anything it calls); disentangling those assertions is
-  // difficult/fragile, and would weaken our general checking of invariants.
-  //
-  // TODO(vtl): Consider making these pure virtual once most things support
-  // being passed over a message pipe.
-  virtual void StartSerializeImplNoLock(Channel* channel,
-                                        size_t* max_size,
-                                        size_t* max_platform_handles);
-  virtual bool EndSerializeAndCloseImplNoLock(
-      Channel* channel,
-      void* destination,
-      size_t* actual_size,
-      embedder::PlatformHandleVector* platform_handles);
-
-  // Available to subclasses. (Note: Returns a non-const reference, just like
-  // |base::AutoLock|'s constructor takes a non-const reference.)
-  base::Lock& lock() const { return lock_; }
-
- private:
-  friend class DispatcherTransport;
-
-  // This should be overridden to return true if/when there's an ongoing
-  // operation (e.g., two-phase read/writes on data pipes) that should prevent a
-  // handle from being sent over a message pipe (with status "busy").
-  virtual bool IsBusyNoLock() const;
-
-  // Closes the dispatcher. This must be done under lock, and unlike |Close()|,
-  // the dispatcher must not be closed already. (This is the "equivalent" of
-  // |CreateEquivalentDispatcherAndCloseNoLock()|, for situations where the
-  // dispatcher must be disposed of instead of "transferred".)
-  void CloseNoLock();
-
-  // Creates an equivalent dispatcher -- representing the same resource as this
-  // dispatcher -- and close (i.e., disable) this dispatcher. I.e., this
-  // dispatcher will look as though it was closed, but the resource it
-  // represents will be assigned to the new dispatcher. This must be called
-  // under the dispatcher's lock.
-  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseNoLock();
-
-  // API to serialize dispatchers to a |Channel|, exposed to only
-  // |TransportData| (via |TransportData|). They may only be called on a
-  // dispatcher attached to a |MessageInTransit| (and in particular not in
-  // |CoreImpl|'s handle table).
-  //
-  // Starts the serialization. Returns (via the two "out" parameters) the
-  // maximum amount of space that may be needed to serialize this dispatcher to
-  // the given |Channel| (no more than
-  // |TransportData::kMaxSerializedDispatcherSize|) and the maximum number of
-  // |PlatformHandle|s that may need to be attached (no more than
-  // |TransportData::kMaxSerializedDispatcherPlatformHandles|). If this
-  // dispatcher cannot be serialized to the given |Channel|, |*max_size| and
-  // |*max_platform_handles| should be set to zero. A call to this method will
-  // ALWAYS be followed by a call to |EndSerializeAndClose()| (even if this
-  // dispatcher cannot be serialized to the given |Channel|).
-  void StartSerialize(Channel* channel,
-                      size_t* max_size,
-                      size_t* max_platform_handles);
-  // Completes the serialization of this dispatcher to the given |Channel| and
-  // closes it. (This call will always follow an earlier call to
-  // |StartSerialize()|, with the same |Channel|.) This does so by writing to
-  // |destination| and appending any |PlatformHandle|s needed to
-  // |platform_handles| (which may be null if no platform handles were indicated
-  // to be required to |StartSerialize()|). This may write no more than the
-  // amount indicated by |StartSerialize()|. (WARNING: Beware of races, e.g., if
-  // something can be mutated between the two calls!) Returns true on success,
-  // in which case |*actual_size| is set to the amount it actually wrote to
-  // |destination|. On failure, |*actual_size| should not be modified; however,
-  // the dispatcher will still be closed.
-  bool EndSerializeAndClose(Channel* channel,
-                            void* destination,
-                            size_t* actual_size,
-                            embedder::PlatformHandleVector* platform_handles);
-
-  // This protects the following members as well as any state added by
-  // subclasses.
-  mutable base::Lock lock_;
-  bool is_closed_;
-
-  DISALLOW_COPY_AND_ASSIGN(Dispatcher);
-};
-
-// Wrapper around a |Dispatcher| pointer, while it's being processed to be
-// passed in a message pipe. See the comment about
-// |Dispatcher::HandleTableAccess| for more details.
-//
-// Note: This class is deliberately "thin" -- no more expensive than a
-// |Dispatcher*|.
-class MOJO_SYSTEM_IMPL_EXPORT DispatcherTransport {
- public:
-  DispatcherTransport() : dispatcher_(nullptr) {}
-
-  void End();
-
-  Dispatcher::Type GetType() const { return dispatcher_->GetType(); }
-  bool IsBusy() const { return dispatcher_->IsBusyNoLock(); }
-  void Close() { dispatcher_->CloseNoLock(); }
-  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndClose() {
-    return dispatcher_->CreateEquivalentDispatcherAndCloseNoLock();
-  }
-
-  bool is_valid() const { return !!dispatcher_; }
-
- protected:
-  Dispatcher* dispatcher() { return dispatcher_; }
-
- private:
-  friend class Dispatcher::HandleTableAccess;
-
-  explicit DispatcherTransport(Dispatcher* dispatcher)
-      : dispatcher_(dispatcher) {}
-
-  Dispatcher* dispatcher_;
-
-  // Copy and assign allowed.
-};
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // MOJO_EDK_SYSTEM_DISPATCHER_H_