X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/d344228734dccb1dc67a1fe7e80825c5e49a8199..d310fbedabd3101505b694f5c25a2e48480a3c2b:/src/syncio.c?ds=sidebyside diff --git a/src/syncio.c b/src/syncio.c index b0c2969e..0c202c9e 100644 --- a/src/syncio.c +++ b/src/syncio.c @@ -42,10 +42,10 @@ #define REDIS_SYNCIO_RESOLUTION 10 /* Resolution in milliseconds */ -/* 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. */ +/* 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(); @@ -56,13 +56,19 @@ ssize_t syncWrite(int fd, char *ptr, ssize_t size, long long timeout) { remaining : REDIS_SYNCIO_RESOLUTION; long long elapsed; - if (aeWait(fd,AE_WRITABLE,wait) & AE_WRITABLE) { - nwritten = write(fd,ptr,size); - if (nwritten == -1) return -1; + /* 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 (size == 0) return ret; } + if (size == 0) return ret; + + /* Wait */ + aeWait(fd,AE_WRITABLE,wait); elapsed = mstime() - start; if (elapsed >= timeout) { errno = ETIMEDOUT; @@ -72,8 +78,8 @@ ssize_t syncWrite(int fd, char *ptr, ssize_t size, long long 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. +/* 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) { @@ -81,19 +87,27 @@ ssize_t syncRead(int fd, char *ptr, ssize_t size, long long timeout) { 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; - if (aeWait(fd,AE_READABLE,wait) & AE_READABLE) { - nread = read(fd,ptr,size); - if (nread <= 0) return -1; + /* 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 (size == 0) return totread; } + if (size == 0) return totread; + + /* Wait */ + aeWait(fd,AE_READABLE,wait); elapsed = mstime() - start; if (elapsed >= timeout) { errno = ETIMEDOUT;