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IXWebSocket/test/compatibility/C/uWebSockets/src/AsyncSocket.h

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C++

/*
* Authored by Alex Hultman, 2018-2019.
* Intellectual property of third-party.
* 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.
*/
#ifndef UWS_ASYNCSOCKET_H
#define UWS_ASYNCSOCKET_H
/* This class implements async socket memory management strategies */
#include "LoopData.h"
#include "AsyncSocketData.h"
namespace uWS {
template <bool, bool> struct WebSocketContext;
template <bool SSL>
struct AsyncSocket {
template <bool> friend struct HttpContext;
template <bool, bool> friend struct WebSocketContext;
template <bool> friend struct WebSocketContextData;
friend struct TopicTree;
protected:
/* Get loop data for socket */
LoopData *getLoopData() {
return (LoopData *) us_loop_ext(us_socket_context_loop(SSL, us_socket_context(SSL, (us_socket_t *) this)));
}
/* Get socket extension */
AsyncSocketData<SSL> *getAsyncSocketData() {
return (AsyncSocketData<SSL> *) us_socket_ext(SSL, (us_socket_t *) this);
}
/* Socket timeout */
void timeout(unsigned int seconds) {
us_socket_timeout(SSL, (us_socket_t *) this, seconds);
}
/* Shutdown socket without any automatic drainage */
void shutdown() {
us_socket_shutdown(SSL, (us_socket_t *) this);
}
/* Immediately close socket */
us_socket_t *close() {
return us_socket_close(SSL, (us_socket_t *) this);
}
/* Cork this socket. Only one socket may ever be corked per-loop at any given time */
void cork() {
/* What if another socket is corked? */
getLoopData()->corkedSocket = this;
}
/* Returns wheter we are corked or not */
bool isCorked() {
return getLoopData()->corkedSocket == this;
}
/* Returns whether we could cork (it is free) */
bool canCork() {
return getLoopData()->corkedSocket == nullptr;
}
/* Returns a suitable buffer for temporary assemblation of send data */
std::pair<char *, bool> getSendBuffer(size_t size) {
/* If we are corked and we have room, return the cork buffer itself */
LoopData *loopData = getLoopData();
if (loopData->corkedSocket == this && loopData->corkOffset + size < LoopData::CORK_BUFFER_SIZE) {
char *sendBuffer = loopData->corkBuffer + loopData->corkOffset;
loopData->corkOffset += (int) size;
return {sendBuffer, false};
} else {
/* Slow path for now, we want to always be corked if possible */
return {(char *) malloc(size), true};
}
}
/* Returns the user space backpressure. */
int getBufferedAmount() {
return (int) getAsyncSocketData()->buffer.size();
}
/* Returns the remote IP address or empty string on failure */
std::string_view getRemoteAddress() {
static thread_local char buf[16];
int ipLength = 16;
us_socket_remote_address(SSL, (us_socket_t *) this, buf, &ipLength);
return std::string_view(buf, ipLength);
}
/* Write in three levels of prioritization: cork-buffer, syscall, socket-buffer. Always drain if possible.
* Returns pair of bytes written (anywhere) and wheter or not this call resulted in the polling for
* writable (or we are in a state that implies polling for writable). */
std::pair<int, bool> write(const char *src, int length, bool optionally = false, int nextLength = 0) {
/* Fake success if closed, simple fix to allow uncork of closed socket to succeed */
if (us_socket_is_closed(SSL, (us_socket_t *) this)) {
return {length, false};
}
LoopData *loopData = getLoopData();
AsyncSocketData<SSL> *asyncSocketData = getAsyncSocketData();
/* We are limited if we have a per-socket buffer */
if (asyncSocketData->buffer.length()) {
/* Write off as much as we can */
int written = us_socket_write(SSL, (us_socket_t *) this, asyncSocketData->buffer.data(), (int) asyncSocketData->buffer.length(), /*nextLength != 0 | */length);
/* On failure return, otherwise continue down the function */
if ((unsigned int) written < asyncSocketData->buffer.length()) {
/* Update buffering (todo: we can do better here if we keep track of what happens to this guy later on) */
asyncSocketData->buffer = asyncSocketData->buffer.substr(written);
if (optionally) {
/* Thankfully we can exit early here */
return {0, true};
} else {
/* This path is horrible and points towards erroneous usage */
asyncSocketData->buffer.append(src, length);
return {length, true};
}
}
/* At this point we simply have no buffer and can continue as normal */
asyncSocketData->buffer.clear();
}
if (length) {
if (loopData->corkedSocket == this) {
/* We are corked */
if (LoopData::CORK_BUFFER_SIZE - loopData->corkOffset >= length) {
/* If the entire chunk fits in cork buffer */
memcpy(loopData->corkBuffer + loopData->corkOffset, src, length);
loopData->corkOffset += length;
/* Fall through to default return */
} else {
/* Strategy differences between SSL and non-SSL regarding syscall minimizing */
if constexpr (SSL) {
/* Cork up as much as we can */
int stripped = LoopData::CORK_BUFFER_SIZE - loopData->corkOffset;
memcpy(loopData->corkBuffer + loopData->corkOffset, src, stripped);
loopData->corkOffset = LoopData::CORK_BUFFER_SIZE;
auto [written, failed] = uncork(src + stripped, length - stripped, optionally);
return {written + stripped, failed};
}
/* For non-SSL we take the penalty of two syscalls */
return uncork(src, length, optionally);
}
} else {
/* We are not corked */
int written = us_socket_write(SSL, (us_socket_t *) this, src, length, nextLength != 0);
/* Did we fail? */
if (written < length) {
/* If the write was optional then just bail out */
if (optionally) {
return {written, true};
}
/* Fall back to worst possible case (should be very rare for HTTP) */
/* At least we can reserve room for next chunk if we know it up front */
if (nextLength) {
asyncSocketData->buffer.reserve(asyncSocketData->buffer.length() + length - written + nextLength);
}
/* Buffer this chunk */
asyncSocketData->buffer.append(src + written, length - written);
/* Return the failure */
return {length, true};
}
/* Fall through to default return */
}
}
/* Default fall through return */
return {length, false};
}
/* Uncork this socket and flush or buffer any corked and/or passed data. It is essential to remember doing this. */
/* It does NOT count bytes written from cork buffer (they are already accounted for in the write call responsible for its corking)! */
std::pair<int, bool> uncork(const char *src = nullptr, int length = 0, bool optionally = false) {
LoopData *loopData = getLoopData();
if (loopData->corkedSocket == this) {
loopData->corkedSocket = nullptr;
if (loopData->corkOffset) {
/* Corked data is already accounted for via its write call */
auto [written, failed] = write(loopData->corkBuffer, loopData->corkOffset, false, length);
loopData->corkOffset = 0;
if (failed) {
/* We do not need to care for buffering here, write does that */
return {0, true};
}
}
/* We should only return with new writes, not things written to cork already */
return write(src, length, optionally, 0);
} else {
/* We are not even corked! */
return {0, false};
}
}
};
}
#endif // UWS_ASYNCSOCKET_H