/* rio.c is a simple stream-oriented I/O abstraction that provides an interface
* to write code that can consume/produce data using different concrete input
* and output devices. For instance the same rdb.c code using the rio
* abstraction can be used to read and write the RDB format using in-memory
* buffers or files.
*
* A rio object provides the following methods:
* read: read from stream.
* write: write to stream.
* tell: get the current offset.
*
* It is also possible to set a 'checksum' method that is used by rio.c in order
* to compute a checksum of the data written or read, or to query the rio object
* for the current checksum.
*
* ----------------------------------------------------------------------------
*
* Copyright (c) 2009-2012, Pieter Noordhuis <pcnoordhuis at gmail dot com>
* Copyright (c) 2009-2012, 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 "fmacros.h"
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include "rio.h"
#include "util.h"
#include "crc64.h"
#include "config.h"
#include "server.h"
/* ------------------------- Buffer I/O implementation ----------------------- */
/* Returns 1 or 0 for success/failure. */
static size_t rioBufferWrite(rio *r, const void *buf, size_t len) {
r->io.buffer.ptr = sdscatlen(r->io.buffer.ptr,(char*)buf,len);
r->io.buffer.pos += len;
return 1;
}
/* Returns 1 or 0 for success/failure. */
static size_t rioBufferRead(rio *r, void *buf, size_t len) {
if (sdslen(r->io.buffer.ptr)-r->io.buffer.pos < len)
return 0; /* not enough buffer to return len bytes. */
memcpy(buf,r->io.buffer.ptr+r->io.buffer.pos,len);
r->io.buffer.pos += len;
return 1;
}
/* Returns read/write position in buffer. */
static off_t rioBufferTell(rio *r) {
return r->io.buffer.pos;
}
/* Flushes any buffer to target device if applicable. Returns 1 on success
* and 0 on failures. */
static int rioBufferFlush(rio *r) {
UNUSED(r);
return 1; /* Nothing to do, our write just appends to the buffer. */
}
static const rio rioBufferIO = {
rioBufferRead,
rioBufferWrite,
rioBufferTell,
rioBufferFlush,
NULL, /* update_checksum */
0, /* current checksum */
0, /* bytes read or written */
0, /* read/write chunk size */
{ { NULL, 0 } } /* union for io-specific vars */
};
void rioInitWithBuffer(rio *r, sds s) {
*r = rioBufferIO;
r->io.buffer.ptr = s;
r->io.buffer.pos = 0;
}
/* --------------------- Stdio file pointer implementation ------------------- */
/* Returns 1 or 0 for success/failure. */
static size_t rioFileWrite(rio *r, const void *buf, size_t len) {
size_t retval;
retval = fwrite(buf,len,1,r->io.file.fp);
r->io.file.buffered += len;
if (r->io.file.autosync &&
r->io.file.buffered >= r->io.file.autosync)
{
fflush(r->io.file.fp);
redis_fsync(fileno(r->io.file.fp));
r->io.file.buffered = 0;
}
return retval;
}
/* Returns 1 or 0 for success/failure. */
static size_t rioFileRead(rio *r, void *buf, size_t len) {
return fread(buf,len,1,r->io.file.fp);
}
/* Returns read/write position in file. */
static off_t rioFileTell(rio *r) {
return ftello(r->io.file.fp);
}
/* Flushes any buffer to target device if applicable. Returns 1 on success
* and 0 on failures. */
static int rioFileFlush(rio *r) {
return (fflush(r->io.file.fp) == 0) ? 1 : 0;
}
static const rio rioFileIO = {
rioFileRead,
rioFileWrite,
rioFileTell,
rioFileFlush,
NULL, /* update_checksum */
0, /* current checksum */
0, /* bytes read or written */
0, /* read/write chunk size */
{ { NULL, 0 } } /* union for io-specific vars */
};
void rioInitWithFile(rio *r, FILE *fp) {
*r = rioFileIO;
r->io.file.fp = fp;
r->io.file.buffered = 0;
r->io.file.autosync = 0;
}
/* ------------------- File descriptors set implementation ------------------- */
/* Returns 1 or 0 for success/failure.
* The function returns success as long as we are able to correctly write
* to at least one file descriptor.
*
* When buf is NULL and len is 0, the function performs a flush operation
* if there is some pending buffer, so this function is also used in order
* to implement rioFdsetFlush(). */
static size_t rioFdsetWrite(rio *r, const void *buf, size_t len) {
ssize_t retval;
int j;
unsigned char *p = (unsigned char*) buf;
int doflush = (buf == NULL && len == 0);
/* To start we always append to our buffer. If it gets larger than
* a given size, we actually write to the sockets. */
if (len) {
r->io.fdset.buf = sdscatlen(r->io.fdset.buf,buf,len);
len = 0; /* Prevent entering the while below if we don't flush. */
if (sdslen(r->io.fdset.buf) > PROTO_IOBUF_LEN) doflush = 1;
}
if (doflush) {
p = (unsigned char*) r->io.fdset.buf;
len = sdslen(r->io.fdset.buf);
}
/* Write in little chunchs so that when there are big writes we
* parallelize while the kernel is sending data in background to
* the TCP socket. */
while(len) {
size_t count = len < 1024 ? len : 1024;
int broken = 0;
for (j = 0; j < r->io.fdset.numfds; j++) {
if (r->io.fdset.state[j] != 0) {
/* Skip FDs alraedy in error. */
broken++;
continue;
}
/* Make sure to write 'count' bytes to the socket regardless
* of short writes. */
size_t nwritten = 0;
while(nwritten != count) {
retval = write(r->io.fdset.fds[j],p+nwritten,count-nwritten);
if (retval <= 0) {
/* With blocking sockets, which is the sole user of this
* rio target, EWOULDBLOCK is returned only because of
* the SO_SNDTIMEO socket option, so we translate the error
* into one more recognizable by the user. */
if (retval == -1 && errno == EWOULDBLOCK) errno = ETIMEDOUT;
break;
}
nwritten += retval;
}
if (nwritten != count) {
/* Mark this FD as broken. */
r->io.fdset.state[j] = errno;
if (r->io.fdset.state[j] == 0) r->io.fdset.state[j] = EIO;
}
}
if (broken == r->io.fdset.numfds) return 0; /* All the FDs in error. */
p += count;
len -= count;
r->io.fdset.pos += count;
}
if (doflush) sdsclear(r->io.fdset.buf);
return 1;
}
/* Returns 1 or 0 for success/failure. */
static size_t rioFdsetRead(rio *r, void *buf, size_t len) {
UNUSED(r);
UNUSED(buf);
UNUSED(len);
return 0; /* Error, this target does not support reading. */
}
/* Returns read/write position in file. */
static off_t rioFdsetTell(rio *r) {
return r->io.fdset.pos;
}
/* Flushes any buffer to target device if applicable. Returns 1 on success
* and 0 on failures. */
static int rioFdsetFlush(rio *r) {
/* Our flush is implemented by the write method, that recognizes a
* buffer set to NULL with a count of zero as a flush request. */
return rioFdsetWrite(r,NULL,0);
}
static const rio rioFdsetIO = {
rioFdsetRead,
rioFdsetWrite,
rioFdsetTell,
rioFdsetFlush,
NULL, /* update_checksum */
0, /* current checksum */
0, /* bytes read or written */
0, /* read/write chunk size */
{ { NULL, 0 } } /* union for io-specific vars */
};
void rioInitWithFdset(rio *r, int *fds, int numfds) {
int j;
*r = rioFdsetIO;
r->io.fdset.fds = zmalloc(sizeof(int)*numfds);
r->io.fdset.state = zmalloc(sizeof(int)*numfds);
memcpy(r->io.fdset.fds,fds,sizeof(int)*numfds);
for (j = 0; j < numfds; j++) r->io.fdset.state[j] = 0;
r->io.fdset.numfds = numfds;
r->io.fdset.pos = 0;
r->io.fdset.buf = sdsempty();
}
/* release the rio stream. */
void rioFreeFdset(rio *r) {
zfree(r->io.fdset.fds);
zfree(r->io.fdset.state);
sdsfree(r->io.fdset.buf);
}
/* ---------------------------- Generic functions ---------------------------- */
/* This function can be installed both in memory and file streams when checksum
* computation is needed. */
void rioGenericUpdateChecksum(rio *r, const void *buf, size_t len) {
r->cksum = crc64(r->cksum,buf,len);
}
/* Set the file-based rio object to auto-fsync every 'bytes' file written.
* By default this is set to zero that means no automatic file sync is
* performed.
*
* This feature is useful in a few contexts since when we rely on OS write
* buffers sometimes the OS buffers way too much, resulting in too many
* disk I/O concentrated in very little time. When we fsync in an explicit
* way instead the I/O pressure is more distributed across time. */
void rioSetAutoSync(rio *r, off_t bytes) {
serverAssert(r->read == rioFileIO.read);
r->io.file.autosync = bytes;
}
/* --------------------------- Higher level interface --------------------------
*
* The following higher level functions use lower level rio.c functions to help
* generating the Redis protocol for the Append Only File. */
/* Write multi bulk count in the format: "*<count>\r\n". */
size_t rioWriteBulkCount(rio *r, char prefix, long count) {
char cbuf[128];
int clen;
cbuf[0] = prefix;
clen = 1+ll2string(cbuf+1,sizeof(cbuf)-1,count);
cbuf[clen++] = '\r';
cbuf[clen++] = '\n';
if (rioWrite(r,cbuf,clen) == 0) return 0;
return clen;
}
/* Write binary-safe string in the format: "$<count>\r\n<payload>\r\n". */
size_t rioWriteBulkString(rio *r, const char *buf, size_t len) {
size_t nwritten;
if ((nwritten = rioWriteBulkCount(r,'$',len)) == 0) return 0;
if (len > 0 && rioWrite(r,buf,len) == 0) return 0;
if (rioWrite(r,"\r\n",2) == 0) return 0;
return nwritten+len+2;
}
/* Write a long long value in format: "$<count>\r\n<payload>\r\n". */
size_t rioWriteBulkLongLong(rio *r, long long l) {
char lbuf[32];
unsigned int llen;
llen = ll2string(lbuf,sizeof(lbuf),l);
return rioWriteBulkString(r,lbuf,llen);
}
/* Write a double value in the format: "$<count>\r\n<payload>\r\n" */
size_t rioWriteBulkDouble(rio *r, double d) {
char dbuf[128];
unsigned int dlen;
dlen = snprintf(dbuf,sizeof(dbuf),"%.17g",d);
return rioWriteBulkString(r,dbuf,dlen);
}