1 files changed, 145 insertions, 0 deletions
diff --git a/src/syncio.c b/src/syncio.c
new file mode 100644
index 0000000..b2843d5
--- /dev/null
+++ b/src/syncio.c
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+/* Synchronous socket and file I/O operations useful across the core.
+ *
+ * Copyright (c) 2009-2010, 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"
+
+/* ----------------- Blocking sockets I/O with timeouts --------------------- */
+
+/* Redis performs most of the I/O in a nonblocking way, with the exception
+ * 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.
+ *
+ * All the functions take the timeout in milliseconds. */
+
+#define 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. */
+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 > SYNCIO__RESOLUTION) ?
+                          remaining : 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 (size == 0) return ret;
+
+        /* Wait */
+        aeWait(fd,AE_WRITABLE,wait);
+        elapsed = mstime() - start;
+        if (elapsed >= timeout) {
+            errno = ETIMEDOUT;
+            return -1;
+        }
+        remaining = timeout - elapsed;
+    }
+}
+
+/* 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;
+    long long start = mstime();
+    long long remaining = timeout;
+
+    if (size == 0) return 0;
+    while(1) {
+        long long wait = (remaining > SYNCIO__RESOLUTION) ?
+                          remaining : 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 (size == 0) return totread;
+
+        /* Wait */
+        aeWait(fd,AE_READABLE,wait);
+        elapsed = mstime() - start;
+        if (elapsed >= timeout) {
+            errno = ETIMEDOUT;
+            return -1;
+        }
+        remaining = timeout - elapsed;
+    }
+}
+
+/* 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--;
+    while(size) {
+        char c;
+
+        if (syncRead(fd,&c,1,timeout) == -1) return -1;
+        if (c == '\n') {
+            *ptr = '\0';
+            if (nread && *(ptr-1) == '\r') *(ptr-1) = '\0';
+            return nread;
+        } else {
+            *ptr++ = c;
+            *ptr = '\0';
+            nread++;
+        }
+        size--;
+    }
+    return nread;
+}