Index: mojo/system/dispatcher.h |
diff --git a/mojo/system/dispatcher.h b/mojo/system/dispatcher.h |
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-// 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_DISPATCHER_H_ |
-#define MOJO_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/embedder/platform_handle.h" |
-#include "mojo/embedder/platform_handle_vector.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" |
-#include "mojo/system/handle_signals_state.h" |
-#include "mojo/system/memory.h" |
-#include "mojo/system/system_impl_export.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_SYSTEM_DISPATCHER_H_ |