X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/0a546fc01758f9a9f8b2113764c2cf963df6ef20..989a7820ca0cb1b88493797fdecd2e7168558859:/src/syncio.c diff --git a/src/syncio.c b/src/syncio.c index 28ac1811..0c202c9e 100644 --- a/src/syncio.c +++ b/src/syncio.c @@ -36,50 +36,93 @@ * of the SYNC command where the slave does it in a blocking way, and * the MIGRATE command that must be blocking in order to be atomic from the * point of view of the two instances (one migrating the key and one receiving - * the key). This is why need the following blocking I/O functions. */ + * the key). This is why need the following blocking I/O functions. + * + * All the functions take the timeout in milliseconds. */ -int syncWrite(int fd, char *ptr, ssize_t size, int timeout) { - ssize_t nwritten, ret = size; - time_t start = time(NULL); +#define REDIS_SYNCIO_RESOLUTION 10 /* Resolution in milliseconds */ - timeout++; - while(size) { - if (aeWait(fd,AE_WRITABLE,1000) & AE_WRITABLE) { - nwritten = write(fd,ptr,size); - if (nwritten == -1) return -1; +/* Write the specified payload to 'fd'. If writing the whole payload will be + * done within 'timeout' milliseconds the operation succeeds and 'size' is + * returned. Otherwise the operation fails, -1 is returned, and an unspecified + * partial write could be performed against the file descriptor. */ +ssize_t syncWrite(int fd, char *ptr, ssize_t size, long long timeout) { + ssize_t nwritten, ret = size; + long long start = mstime(); + long long remaining = timeout; + + while(1) { + long long wait = (remaining > REDIS_SYNCIO_RESOLUTION) ? + remaining : REDIS_SYNCIO_RESOLUTION; + long long elapsed; + + /* Optimistically try to write before checking if the file descriptor + * is actually writable. At worst we get EAGAIN. */ + nwritten = write(fd,ptr,size); + if (nwritten == -1) { + if (errno != EAGAIN) return -1; + } else { ptr += nwritten; size -= nwritten; } - if ((time(NULL)-start) > timeout) { + if (size == 0) return ret; + + /* Wait */ + aeWait(fd,AE_WRITABLE,wait); + elapsed = mstime() - start; + if (elapsed >= timeout) { errno = ETIMEDOUT; return -1; } + remaining = timeout - elapsed; } - return ret; } -int syncRead(int fd, char *ptr, ssize_t size, int timeout) { +/* Read the specified amount of bytes from 'fd'. If all the bytes are read + * within 'timeout' milliseconds the operation succeed and 'size' is returned. + * Otherwise the operation fails, -1 is returned, and an unspecified amount of + * data could be read from the file descriptor. */ +ssize_t syncRead(int fd, char *ptr, ssize_t size, long long timeout) { ssize_t nread, totread = 0; - time_t start = time(NULL); - - timeout++; - while(size) { - if (aeWait(fd,AE_READABLE,1000) & AE_READABLE) { - nread = read(fd,ptr,size); - if (nread <= 0) return -1; + long long start = mstime(); + long long remaining = timeout; + + if (size == 0) return 0; + while(1) { + long long wait = (remaining > REDIS_SYNCIO_RESOLUTION) ? + remaining : REDIS_SYNCIO_RESOLUTION; + long long elapsed; + + /* Optimistically try to read before checking if the file descriptor + * is actually readable. At worst we get EAGAIN. */ + nread = read(fd,ptr,size); + if (nread == 0) return -1; /* short read. */ + if (nread == -1) { + if (errno != EAGAIN) return -1; + } else { ptr += nread; size -= nread; totread += nread; } - if ((time(NULL)-start) > timeout) { + if (size == 0) return totread; + + /* Wait */ + aeWait(fd,AE_READABLE,wait); + elapsed = mstime() - start; + if (elapsed >= timeout) { errno = ETIMEDOUT; return -1; } + remaining = timeout - elapsed; } - return totread; } -int syncReadLine(int fd, char *ptr, ssize_t size, int timeout) { +/* Read a line making sure that every char will not require more than 'timeout' + * milliseconds to be read. + * + * On success the number of bytes read is returned, otherwise -1. + * On success the string is always correctly terminated with a 0 byte. */ +ssize_t syncReadLine(int fd, char *ptr, ssize_t size, long long timeout) { ssize_t nread = 0; size--; @@ -99,56 +142,3 @@ int syncReadLine(int fd, char *ptr, ssize_t size, int timeout) { } return nread; } - -/* ----------------- Blocking sockets I/O with timeouts --------------------- */ - -/* Write binary-safe string into a file in the bulkformat - * $\r\n\r\n */ -int fwriteBulkString(FILE *fp, char *s, unsigned long len) { - char cbuf[128]; - int clen; - cbuf[0] = '$'; - clen = 1+ll2string(cbuf+1,sizeof(cbuf)-1,len); - cbuf[clen++] = '\r'; - cbuf[clen++] = '\n'; - if (fwrite(cbuf,clen,1,fp) == 0) return 0; - if (len > 0 && fwrite(s,len,1,fp) == 0) return 0; - if (fwrite("\r\n",2,1,fp) == 0) return 0; - return 1; -} - -/* Write a double value in bulk format $\r\n\r\n */ -int fwriteBulkDouble(FILE *fp, double d) { - char buf[128], dbuf[128]; - - snprintf(dbuf,sizeof(dbuf),"%.17g\r\n",d); - snprintf(buf,sizeof(buf),"$%lu\r\n",(unsigned long)strlen(dbuf)-2); - if (fwrite(buf,strlen(buf),1,fp) == 0) return 0; - if (fwrite(dbuf,strlen(dbuf),1,fp) == 0) return 0; - return 1; -} - -/* Write a long value in bulk format $\r\n\r\n */ -int fwriteBulkLongLong(FILE *fp, long long l) { - char bbuf[128], lbuf[128]; - unsigned int blen, llen; - llen = ll2string(lbuf,32,l); - blen = snprintf(bbuf,sizeof(bbuf),"$%u\r\n%s\r\n",llen,lbuf); - if (fwrite(bbuf,blen,1,fp) == 0) return 0; - return 1; -} - -/* Delegate writing an object to writing a bulk string or bulk long long. */ -int fwriteBulkObject(FILE *fp, robj *obj) { - /* Avoid using getDecodedObject to help copy-on-write (we are often - * in a child process when this function is called). */ - if (obj->encoding == REDIS_ENCODING_INT) { - return fwriteBulkLongLong(fp,(long)obj->ptr); - } else if (obj->encoding == REDIS_ENCODING_RAW) { - return fwriteBulkString(fp,obj->ptr,sdslen(obj->ptr)); - } else { - redisPanic("Unknown string encoding"); - } -} - -