Child -> Parent pipe for COW info transferring.

1 files changed, 83 insertions, 0 deletions

diff --git a/src/childinfo.c b/src/childinfo.c
new file mode 100644
index 000000000..123c20421
--- /dev/null
+++ b/src/childinfo.c
@@ -0,0 +1,83 @@
+/*
+ * 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>
+
+/* 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 cloesChildInfoPipe() since can't hurt. */
+        closeChildInfoPipe();
+    } else if (anetNonBlock(NULL,server.child_info_pipe[0]) != ANET_OK) {
+        closeChildInfoPipe();
+    }
+}
+
+/* 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;
+    }
+}
+
+/* Send COW data to parent. The child should call this function after populating
+ * the corresponding fields it want to sent (according to the process type). */
+void sendChildInfo(int ptype) {
+    if (server.child_info_pipe[1] == -1) return;
+    server.child_info_data.magic = CHILD_INFO_MAGIC;
+    server.child_info_data.process_type = ptype;
+    ssize_t wlen = sizeof(server.child_info_data);
+    if (write(server.child_info_pipe[1],&server.child_info_data,wlen) != wlen) {
+        /* Nothing to do on error, this will be detected by the other side. */
+    }
+}
+
+/* Receive COW data from parent. */
+void receiveChildInfo(void) {
+    if (server.child_info_pipe[0] == -1) return;
+    ssize_t wlen = sizeof(server.child_info_data);
+    if (read(server.child_info_pipe[0],&server.child_info_data,wlen) == wlen &&
+        server.child_info_data.magic == CHILD_INFO_MAGIC)
+    {
+        if (server.child_info_data.process_type == CHILD_INFO_TYPE_RDB) {
+            server.stat_rdb_cow_bytes = server.child_info_data.cow_size;
+        } else if (server.child_info_data.process_type == CHILD_INFO_TYPE_AOF) {
+            server.stat_aof_cow_bytes = server.child_info_data.cow_size;
+        }
+    }
+}