1 files changed, 183 insertions, 0 deletions
diff --git a/src/childinfo.c b/src/childinfo.c
new file mode 100644
index 0000000..1303dd0
--- /dev/null
+++ b/src/childinfo.c
@@ -0,0 +1,183 @@
+/*
+ * 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>
+#include <fcntl.h>
+
+typedef struct {
+    size_t keys;
+    size_t cow;
+    monotime cow_updated;
+    double progress;
+    childInfoType information_type; /* Type of information */
+} child_info_data;
+
+/* 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 (anetPipe(server.child_info_pipe, O_NONBLOCK, 0) == -1) {
+        /* On error our two file descriptors should be still set to -1,
+         * but we call anyway closeChildInfoPipe() since can't hurt. */
+        closeChildInfoPipe();
+    } else {
+        server.child_info_nread = 0;
+    }
+}
+
+/* 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;
+        server.child_info_nread = 0;
+    }
+}
+
+/* Send save data to parent. */
+void sendChildInfoGeneric(childInfoType info_type, size_t keys, double progress, char *pname) {
+    if (server.child_info_pipe[1] == -1) return;
+
+    static monotime cow_updated = 0;
+    static uint64_t cow_update_cost = 0;
+    static size_t cow = 0;
+    static size_t peak_cow = 0;
+    static size_t update_count = 0;
+    static unsigned long long sum_cow = 0;
+
+    child_info_data data = {0}; /* zero everything, including padding to satisfy valgrind */
+
+    /* When called to report current info, we need to throttle down CoW updates as they
+     * can be very expensive. To do that, we measure the time it takes to get a reading
+     * and schedule the next reading to happen not before time*CHILD_COW_COST_FACTOR
+     * passes. */
+
+    monotime now = getMonotonicUs();
+    if (info_type != CHILD_INFO_TYPE_CURRENT_INFO ||
+        !cow_updated ||
+        now - cow_updated > cow_update_cost * CHILD_COW_DUTY_CYCLE)
+    {
+        cow = zmalloc_get_private_dirty(-1);
+        cow_updated = getMonotonicUs();
+        cow_update_cost = cow_updated - now;
+        if (cow > peak_cow) peak_cow = cow;
+        sum_cow += cow;
+        update_count++;
+
+        int cow_info = (info_type != CHILD_INFO_TYPE_CURRENT_INFO);
+        if (cow || cow_info) {
+            serverLog(cow_info ? LL_NOTICE : LL_VERBOSE,
+                      "Fork CoW for %s: current %zu MB, peak %zu MB, average %llu MB",
+                      pname, cow>>20, peak_cow>>20, (sum_cow/update_count)>>20);
+        }
+    }
+
+    data.information_type = info_type;
+    data.keys = keys;
+    data.cow = cow;
+    data.cow_updated = cow_updated;
+    data.progress = progress;
+
+    ssize_t wlen = sizeof(data);
+
+    if (write(server.child_info_pipe[1], &data, wlen) != wlen) {
+        /* Failed writing to parent, it could have been killed, exit. */
+        serverLog(LL_WARNING,"Child failed reporting info to parent, exiting. %s", strerror(errno));
+        exitFromChild(1);
+    }
+}
+
+/* Update Child info. */
+void updateChildInfo(childInfoType information_type, size_t cow, monotime cow_updated, size_t keys, double progress) {
+    if (cow > server.stat_current_cow_peak) server.stat_current_cow_peak = cow;
+
+    if (information_type == CHILD_INFO_TYPE_CURRENT_INFO) {
+        server.stat_current_cow_bytes = cow;
+        server.stat_current_cow_updated = cow_updated;
+        server.stat_current_save_keys_processed = keys;
+        if (progress != -1) server.stat_module_progress = progress;
+    } else if (information_type == CHILD_INFO_TYPE_AOF_COW_SIZE) {
+        server.stat_aof_cow_bytes = server.stat_current_cow_peak;
+    } else if (information_type == CHILD_INFO_TYPE_RDB_COW_SIZE) {
+        server.stat_rdb_cow_bytes = server.stat_current_cow_peak;
+    } else if (information_type == CHILD_INFO_TYPE_MODULE_COW_SIZE) {
+        server.stat_module_cow_bytes = server.stat_current_cow_peak;
+    }
+}
+
+/* Read child info data from the pipe.
+ * if complete data read into the buffer, 
+ * data is stored into *buffer, and returns 1.
+ * otherwise, the partial data is left in the buffer, waiting for the next read, and returns 0. */
+int readChildInfo(childInfoType *information_type, size_t *cow, monotime *cow_updated, size_t *keys, double* progress) {
+    /* We are using here a static buffer in combination with the server.child_info_nread to handle short reads */
+    static child_info_data buffer;
+    ssize_t wlen = sizeof(buffer);
+
+    /* Do not overlap */
+    if (server.child_info_nread == wlen) server.child_info_nread = 0;
+
+    int nread = read(server.child_info_pipe[0], (char *)&buffer + server.child_info_nread, wlen - server.child_info_nread);
+    if (nread > 0) {
+        server.child_info_nread += nread;
+    }
+
+    /* We have complete child info */
+    if (server.child_info_nread == wlen) {
+        *information_type = buffer.information_type;
+        *cow = buffer.cow;
+        *cow_updated = buffer.cow_updated;
+        *keys = buffer.keys;
+        *progress = buffer.progress;
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
+/* Receive info data from child. */
+void receiveChildInfo(void) {
+    if (server.child_info_pipe[0] == -1) return;
+
+    size_t cow;
+    monotime cow_updated;
+    size_t keys;
+    double progress;
+    childInfoType information_type;
+
+    /* Drain the pipe and update child info so that we get the final message. */
+    while (readChildInfo(&information_type, &cow, &cow_updated, &keys, &progress)) {
+        updateChildInfo(information_type, cow, cow_updated, keys, progress);
+    }
+}