| // Copyright 2017 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_PUBLIC_CPP_SYSTEM_DATA_PIPE_PRODUCER_H_ |
| #define MOJO_PUBLIC_CPP_SYSTEM_DATA_PIPE_PRODUCER_H_ |
| |
| #include <memory> |
| |
| #include "base/callback_forward.h" |
| #include "base/containers/span.h" |
| #include "base/macros.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/memory/weak_ptr.h" |
| #include "mojo/public/cpp/system/data_pipe.h" |
| #include "mojo/public/cpp/system/system_export.h" |
| |
| namespace mojo { |
| |
| // Helper class which takes ownership of a ScopedDataPipeProducerHandle and |
| // assumes responsibility for feeding it the contents of a DataSource. This |
| // takes care of waiting for pipe capacity as needed, and can notify callers |
| // asynchronously when the operation is complete. |
| // |
| // Note that the DataPipeProducer must be kept alive until notified of |
| // completion to ensure that all of the intended contents are written to the |
| // pipe. Premature destruction may result in partial or total truncation of data |
| // made available to the consumer. |
| class MOJO_CPP_SYSTEM_EXPORT DataPipeProducer { |
| public: |
| using CompletionCallback = base::OnceCallback<void(MojoResult result)>; |
| // Interface definition of abstracted content reader that has minimum |
| // base::File equivalent interface to read content. |
| class DataSource { |
| public: |
| // Used as a return value for Read(). |
| struct ReadResult { |
| // The number of bytes read. If returned |bytes_read| is less than |
| // requested size, it means EOF is reached. |
| uint64_t bytes_read = 0; |
| |
| // MojoResult resulting from this call. |
| MojoResult result = MOJO_RESULT_OK; |
| }; |
| virtual ~DataSource() {} |
| |
| // Returns maximum data size. Actual size can be smaller. Used as a hint to |
| // adjust internal read buffer size. |
| virtual uint64_t GetLength() const = 0; |
| |
| // Similar to base::File::Read(), reads the given number of bytes (or until |
| // EOF is reached) starting with the given offset. Returns ReadResult to |
| // represent the number of bytes read and errors. |
| virtual ReadResult Read(uint64_t offset, base::span<char> buffer) = 0; |
| |
| // Notifies DataPipeProducer aborts read operations. |
| virtual void Abort() {} |
| }; |
| |
| // Constructs a new DataPipeProducer which will write data to |producer|. |
| explicit DataPipeProducer(ScopedDataPipeProducerHandle producer); |
| ~DataPipeProducer(); |
| |
| // Attempts to eventually write all of |data_source|'s contents to the pipe. |
| // Invokes |callback| asynchronously when done. Note that |callback| IS |
| // allowed to delete this DataPipeProducer. |
| // |
| // If the write is successful |result| will be |MOJO_RESULT_OK|. Otherwise |
| // (e.g. if the producer detects the consumer is closed and the pipe has no |
| // remaining capacity, or if file open/reads fail for any reason) |result| |
| // will be one of the following: |
| // |
| // |MOJO_RESULT_ABORTED| |
| // |MOJO_RESULT_NOT_FOUND| |
| // |MOJO_RESULT_PERMISSION_DENIED| |
| // |MOJO_RESULT_RESOURCE_EXHAUSTED| |
| // |MOJO_RESULT_UNKNOWN| |
| // |
| // Note that if the DataPipeProducer is destroyed before |callback| can be |
| // invoked, |callback| is *never* invoked, and the write will be permanently |
| // interrupted (and the producer handle closed) after making potentially only |
| // partial progress. |
| // |
| // Multiple writes may be performed in sequence (each one after the last |
| // completes), but Write() must not be called before the |callback| for the |
| // previous call to Write() (if any) has returned. |
| void Write(std::unique_ptr<DataSource> reader, CompletionCallback callback); |
| |
| private: |
| class SequenceState; |
| |
| void InitializeNewRequest(CompletionCallback callback); |
| void OnWriteComplete(CompletionCallback callback, |
| ScopedDataPipeProducerHandle producer, |
| MojoResult result); |
| |
| ScopedDataPipeProducerHandle producer_; |
| scoped_refptr<SequenceState> sequence_state_; |
| base::WeakPtrFactory<DataPipeProducer> weak_factory_{this}; |
| |
| DISALLOW_COPY_AND_ASSIGN(DataPipeProducer); |
| }; |
| |
| } // namespace mojo |
| |
| #endif // MOJO_PUBLIC_CPP_SYSTEM_DATA_PIPE_PRODUCER_H_ |