| #pragma once |
| |
| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| // Memory layout for byte-oriented circular queues |
| |
| #include <atomic> |
| #include <cstdint> |
| |
| #include "common/vsoc/shm/base.h" |
| #include "common/vsoc/shm/lock.h" |
| |
| namespace vsoc { |
| class RegionSignalingInterface; |
| namespace layout { |
| |
| /** |
| * Base classes for all spinlock protected circular queues. |
| * This class should be embedded in the per-region data structure that is used |
| * as the parameter to TypedRegion. |
| */ |
| template <uint32_t SizeLog2> |
| class CircularQueueBase { |
| CircularQueueBase() = delete; |
| CircularQueueBase(const CircularQueueBase&) = delete; |
| CircularQueueBase& operator=(const CircularQueueBase&) = delete; |
| |
| protected: |
| /** |
| * Specifies a part of the queue. Note, the given indexes must be masked |
| * before they can be used against buffer_ |
| */ |
| struct Range { |
| // Points to the first bytes that is part of the range |
| uint32_t start_idx; |
| // Points to the first byte that is not in the range. This is similar to |
| // the STL end iterator. |
| uint32_t end_idx; |
| }; |
| static const uintptr_t BufferSize = (1 << SizeLog2); |
| |
| /** |
| * Copy bytes from buffer_in into the part of the queue specified by Range. |
| */ |
| void CopyInRange(const char* buffer_in, const Range& t); |
| |
| /** |
| * Copy the bytes specified by range to the given buffer. They caller must |
| * ensure that the buffer is large enough to hold the content of the range. |
| */ |
| void CopyOutRange(const Range& t, char* buffer_out); |
| |
| /** |
| * Wait until data becomes available in the queue. The caller must have |
| * called Lock() before invoking this. The caller must call Unlock() |
| * after this returns. |
| */ |
| void WaitForDataLocked(RegionSignalingInterface* r); |
| |
| /** |
| * Reserve space in the queue for writing. The caller must have called Lock() |
| * before invoking this. The caller must call Unlock() after this returns. |
| * Indexes pointing to the reserved space will be placed in range. |
| * On success this returns bytes. |
| * On failure a negative errno indicates the problem. -ENOSPC indicates that |
| * bytes > the queue size, -EWOULDBLOCK indicates that the call would block |
| * waiting for space but was requested non bloking. |
| */ |
| intptr_t WriteReserveLocked(RegionSignalingInterface* r, size_t bytes, |
| Range* t, bool non_blocking); |
| |
| // Note: Both of these fields may hold values larger than the buffer size, |
| // they should be interpreted modulo the buffer size. This fact along with the |
| // buffer size being a power of two greatly simplyfies the index calculations. |
| // Advances when a reader has finished with buffer space |
| std::atomic<uint32_t> r_released_; |
| // Advances when buffer space is filled and ready for a reader |
| std::atomic<uint32_t> w_pub_; |
| // Spinlock that protects the region. 0 means unlocked |
| SpinLock lock_; |
| // The actual memory in the buffer |
| char buffer_[BufferSize]; |
| }; |
| using CircularQueueBase64k = CircularQueueBase<16>; |
| ASSERT_SHM_COMPATIBLE(CircularQueueBase64k, multi_region); |
| |
| /** |
| * Byte oriented circular queue. Reads will always return some data, but |
| * may return less data than requested. Writes will always write all of the |
| * data or return an error. |
| */ |
| template <uint32_t SizeLog2> |
| class CircularByteQueue : public CircularQueueBase<SizeLog2> { |
| public: |
| /** |
| * Read at most max_size bytes from the qeueue, placing them in buffer_out |
| */ |
| intptr_t Read(RegionSignalingInterface* r, char* buffer_out, |
| std::size_t max_size); |
| /** |
| * Write all of the given bytes into the queue. If non_blocking isn't set the |
| * call may block until there is enough available space in the queue. On |
| * success the return value will match bytes. On failure a negative errno is |
| * returned. -ENOSPC: If the queue size is smaller than the number of bytes to |
| * write. -EWOULDBLOCK: If non_blocking is true and there is not enough free |
| * space. |
| */ |
| intptr_t Write(RegionSignalingInterface* r, const char* buffer_in, |
| std::size_t bytes, bool non_blocking = false); |
| |
| protected: |
| using Range = typename CircularQueueBase<SizeLog2>::Range; |
| }; |
| using CircularByteQueue64k = CircularByteQueue<16>; |
| ASSERT_SHM_COMPATIBLE(CircularByteQueue64k, multi_region); |
| |
| /** |
| * Packet oriented circular queue. Reads will either return data or an error. |
| * Each return from read corresponds to a call to write and returns all of the |
| * data from that corresponding Write(). |
| */ |
| template <uint32_t SizeLog2, uint32_t MaxPacketSize> |
| class CircularPacketQueue : public CircularQueueBase<SizeLog2> { |
| public: |
| /** |
| * Read a single packet from the queue, placing its data into buffer_out. |
| * If max_size indicates that buffer_out cannot hold the entire packet |
| * this function will return -ENOSPC. |
| */ |
| intptr_t Read(RegionSignalingInterface* r, char* buffer_out, |
| std::size_t max_size); |
| |
| /** |
| * Writes [buffer_in, buffer_in + bytes) to the queue. |
| * If the number of bytes to be written exceeds the size of the queue |
| * -ENOSPC will be returned. |
| * If non_blocking is true and there is not enough free space on the queue to |
| * write all the data -EWOULDBLOCK will be returned. |
| */ |
| intptr_t Write(RegionSignalingInterface* r, const char* buffer_in, |
| uint32_t bytes, bool non_blocking = false); |
| |
| protected: |
| static_assert(CircularQueueBase<SizeLog2>::BufferSize >= MaxPacketSize, |
| "Buffer is too small to hold the maximum sized packet"); |
| using Range = typename CircularQueueBase<SizeLog2>::Range; |
| intptr_t CalculateBufferedSize(size_t payload); |
| }; |
| using CircularPacketQueue64k = CircularPacketQueue<16, 1024>; |
| ASSERT_SHM_COMPATIBLE(CircularPacketQueue64k, multi_region); |
| |
| } // namespace layout |
| } // namespace vsoc |