boost asio tcp服务器的实现

/* * MMORPG Server * Copyright (C) 2013 * */ #include "CircularBuffer.h" /** Constructor */ CircularBuffer::CircularBuffer() { m_buffer = m_bufferEnd = m_regionAPointer = m_regionBPointer = nullptr; m_regionASize = m_regionBSize = 0; } /** Destructor */ CircularBuffer::~CircularBuffer() { free(m_buffer); } /** Read bytes from the buffer * @param destination pointer to destination where bytes will be written * @param bytes number of bytes to read * @return true if there was enough data, false otherwise */ bool CircularBuffer::Read(void * destination, size_t bytes) { // copy as much out of region a uint8* ptr = (uint8*)destination; size_t read_count = 0; if ((m_regionASize + m_regionBSize) < bytes) return false; // If we have both region A and region B, always "finish" off region A first, as // this will contain the "oldest" data if (bytes > 0 && m_regionASize > 0) { read_count = std::min(bytes, m_regionASize); memcpy(ptr, m_regionAPointer, read_count); m_regionASize -= read_count; m_regionAPointer += read_count; ptr += read_count; bytes -= read_count; } // Data left over? read the data from buffer B if (bytes > 0) { memcpy(ptr, m_regionBPointer, bytes); m_regionBSize -= bytes; m_regionBPointer += bytes; } // Is buffer A empty?, move buffer B to buffer A, to increase future per formance if (m_regionASize == 0) { if (m_regionBSize > 0 && m_regionBPointer != m_buffer) memmove(m_buffer, m_regionBPointer, m_regionBSize); m_regionAPointer = m_buffer; m_regionASize = m_regionBSize; m_regionBPointer = NULL; m_regionBSize = 0; } return true; } /** Write bytes to the buffer * @param data pointer to the data to be written * @param bytes number of bytes to be written * @return true if was successful, otherwise false */ bool CircularBuffer::Write(const void * data, size_t bytes) { // If buffer B exists, write to it. if (m_regionBPointer != NULL) { if (GetBFreeSpace() < bytes) return false; memcpy(&m_regionBPointer[m_regionBSize], data, bytes); m_regionBSize += bytes; return true; } // Otherwise, write to buffer A, or initialize buffer B depending on which has more space. if (GetAFreeSpace() < GetSpaceBeforeA()) { AllocateB(); if (GetBFreeSpace() < bytes) return false; memcpy(&m_regionBPointer[m_regionBSize], data, bytes); m_regionBSize += bytes; return true; } else { if (GetAFreeSpace() < bytes) return false; memcpy(&m_regionAPointer[m_regionASize], data, bytes); m_regionASize += bytes; return true; } } /** Returns the number of available bytes left. */ size_t CircularBuffer::GetSpace() { if( m_regionBPointer != NULL ) return GetBFreeSpace(); else { // would allocating buffer B get us more data? if( GetAFreeSpace() < GetSpaceBeforeA() ) { AllocateB(); return GetBFreeSpace(); } // or not? return GetAFreeSpace(); } } /** Removes len bytes from the front of the buffer * @param len the number of bytes to "cut" */ void CircularBuffer::Remove(size_t len) { // remove from A first before we remove from b size_t remove_count = 0; // If we have both region A and region B, always "finish" off region A first, as // this will contain the "oldest" data if (len > 0 && m_regionASize > 0) { remove_count = std::min(len, m_regionASize); m_regionASize -= remove_count; m_regionAPointer += remove_count; len -= remove_count; } // Data left over? cut the data from buffer B if (len > 0 && m_regionBSize > 0) { remove_count = std::min(len, m_regionBSize); m_regionBSize -= remove_count; m_regionBPointer += remove_count; len -= remove_count; } // is buffer A empty? move buffer B to buffer A, to increase future performance if (m_regionASize == 0) { if (m_regionBSize > 0 && m_regionBPointer != m_buffer) memmove(m_buffer, m_regionBPointer, m_regionBSize); m_regionAPointer = m_buffer; m_regionASize = m_regionBSize; m_regionBPointer = NULL; m_regionBSize = 0; } } /** Allocate the buffer with room for size bytes * @param size the number of bytes to allocate */ void CircularBuffer::Allocate(size_t size) { m_buffer = (uint8*)malloc(size); m_bufferEnd = m_buffer + size; m_regionAPointer = m_buffer; // reset A to the start } /** Increments the "writen" pointer forward len bytes * @param len number of bytes to step */ void CircularBuffer::IncrementWritten(size_t len) // known as "commit" { if( m_regionBPointer != nullptr ) m_regionBSize += len; else m_regionASize += len; } /** Returns a pointer at the "beginning" of the buffer, where data can be pulled from */ void * CircularBuffer::GetBufferStart() { if( m_regionASize > 0 ) return m_regionAPointer; else return m_regionBPointer; }