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/*
* Copyright (c) 2016, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "server.h"
#include <unistd.h>
typedef struct {
int process_type; /* AOF or RDB child? */
int on_exit; /* COW size of active or exited child */
size_t cow_size; /* Copy on write size. */
} child_info_data;
/* Open a child-parent channel used in order to move information about the
* RDB / AOF saving process from the child to the parent (for instance
* the amount of copy on write memory used) */
void openChildInfoPipe(void) {
if (pipe(server.child_info_pipe) == -1) {
/* On error our two file descriptors should be still set to -1,
* but we call anyway closeChildInfoPipe() since can't hurt. */
closeChildInfoPipe();
} else if (anetNonBlock(NULL,server.child_info_pipe[0]) != ANET_OK) {
closeChildInfoPipe();
} else {
server.child_info_nread = 0;
}
}
/* Close the pipes opened with openChildInfoPipe(). */
void closeChildInfoPipe(void) {
if (server.child_info_pipe[0] != -1 ||
server.child_info_pipe[1] != -1)
{
close(server.child_info_pipe[0]);
close(server.child_info_pipe[1]);
server.child_info_pipe[0] = -1;
server.child_info_pipe[1] = -1;
server.child_info_nread = 0;
}
}
/* Send COW data to parent. */
void sendChildInfo(int process_type, int on_exit, size_t cow_size) {
if (server.child_info_pipe[1] == -1) return;
child_info_data buffer = {.process_type = process_type, .on_exit = on_exit, .cow_size = cow_size};
ssize_t wlen = sizeof(buffer);
if (write(server.child_info_pipe[1],&buffer,wlen) != wlen) {
/* Nothing to do on error, this will be detected by the other side. */
}
}
/* Update COW data. */
void updateChildInfo(int process_type, int on_exit, size_t cow_size) {
if (!on_exit) {
server.stat_current_cow_bytes = cow_size;
return;
}
if (process_type == CHILD_TYPE_RDB) {
server.stat_rdb_cow_bytes = cow_size;
} else if (process_type == CHILD_TYPE_AOF) {
server.stat_aof_cow_bytes = cow_size;
} else if (process_type == CHILD_TYPE_MODULE) {
server.stat_module_cow_bytes = cow_size;
}
}
/* Read COW info data from the pipe.
* if complete data read into the buffer, process type, copy-on-write type and copy-on-write size
* are stored into *process_type, *on_exit and *cow_size respectively and returns 1.
* otherwise, the partial data is left in the buffer, waiting for the next read, and returns 0. */
int readChildInfo(int *process_type, int *on_exit, size_t *cow_size) {
/* We are using here a static buffer in combination with the server.child_info_nread to handle short reads */
static child_info_data buffer;
ssize_t wlen = sizeof(buffer);
/* Do not overlap */
if (server.child_info_nread == wlen) server.child_info_nread = 0;
int nread = read(server.child_info_pipe[0], (char *)&buffer + server.child_info_nread, wlen - server.child_info_nread);
if (nread > 0) {
server.child_info_nread += nread;
}
/* We have complete child info */
if (server.child_info_nread == wlen) {
*process_type = buffer.process_type;
*on_exit = buffer.on_exit;
*cow_size = buffer.cow_size;
return 1;
} else {
return 0;
}
}
/* Receive COW data from child. */
void receiveChildInfo(void) {
if (server.child_info_pipe[0] == -1) return;
int process_type;
int on_exit;
size_t cow_size;
/* Drain the pipe and update child info so that we get the final message. */
while (readChildInfo(&process_type, &on_exit, &cow_size)) {
updateChildInfo(process_type, on_exit, cow_size);
}
}
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