Use random poll-interval for appInfo on channel reset.

In few workflows like instant clone, when a large number of VMs are
cloned at the same time, if the appinfo plugin runs at the same time
in all the VMs, the underlying ESXi may encounter heavy load.  To
avoid these situations, a random poll interval should be used
for the appinfo whenever applicable workflows are detected.

Detecting a 'rpc channel reset' is a simple approach to detect.

In this changeset, add the following changes:

- Added a new callback function for the 'rpc channel reset'.  If
the rpc channel is reset, a new random poll interval is calculated
and poll timer is adjusted accordingly.  If the existing appinfo
poll interval is greater than the minimum interval of 30 seconds,
random interval will be generated between 30 and appinfopollinterval.
If the existing poll interval is less than the minimum 30 seconds
time, then random interval will not be changed.

- Code refactoring for few functions.
- Changed one global variable as static.
- Added few debug/info log messages.

diff --git a/open-vm-tools/services/plugins/appInfo/appInfo.c b/open-vm-tools/services/plugins/appInfo/appInfo.c
index 22f3425f9d525128c9dbc875a952d5dc91482987..d96d9a075b2acf713ab0584f60dbd34703e0627e 100644 (file)
--- a/open-vm-tools/services/plugins/appInfo/appInfo.c
+++ b/open-vm-tools/services/plugins/appInfo/appInfo.c
@@ -86,13 +86,15 @@ VM_EMBED_VERSION(VMTOOLSD_VERSION_STRING);
  *
  * This value is controlled by the appinfo.poll-interval config file option.
  */
-int gAppInfoPollInterval = 0;
+static guint gAppInfoPollInterval = 0;
 
 /**
  * AppInfo gather loop timeout source.
  */
 static GSource *gAppInfoTimeoutSource = NULL;
 
+static void TweakGatherLoop(ToolsAppCtx *ctx);
+
 
 /*
  *****************************************************************************
@@ -390,11 +392,12 @@ abort:
  * AppInfoGather --
  *
  * Creates a new thread that collects all the desired application related
- * information and udates the VMX.
+ * information and updates the VMX. Tweaks the poll gather loop as per the
+ * tools configuration after creating the thread.
  *
  * @param[in]  data     The application context.
  *
- * @return TRUE to indicate that the timer should be rescheduled.
+ * @return G_SOURCE_REMOVE to indicate that the timer should be removed.
  *
  *****************************************************************************
  */
@@ -403,104 +406,116 @@ static gboolean
 AppInfoGather(gpointer data)      // IN
 {
    ToolsAppCtx *ctx = data;
+
+   g_debug("%s: Submitting a task to capture application information.\n",
+           __FUNCTION__);
+
    if (!ToolsCorePool_SubmitTask(ctx, AppInfoGatherTask, NULL, NULL)) {
-      g_warning("%s: failed to start information gather thread\n",
-                __FUNCTION__);
+      g_warning("%s: Failed to submit the task for capturing application "
+                "information\n", __FUNCTION__);
    }
 
-   return TRUE;
+   TweakGatherLoop(ctx);
+
+   return G_SOURCE_REMOVE;
 }
 
 
 /*
  *****************************************************************************
- * TweakGatherLoop --
+ * TweakGatherLoopEx --
  *
- * @brief Start, stop, reconfigure a GuestInfoGather poll loop.
+ * Start, stop, reconfigure a AppInfo Gather poll loop.
  *
  * This function is responsible for creating, manipulating, and resetting a
- * AppDiscoveryGather loop timeout source.
+ * AppInfo Gather loop timeout source. The poll loop will be disabled if
+ * the poll interval is 0.
  *
  * @param[in]     ctx           The application context.
- * @param[in]     enable        Whether to enable the gather loop.
+ * @param[in]     pollInterval  Poll interval in seconds. A value of 0 will
+ *                              disable the loop.
  *
  *****************************************************************************
  */
 
 static void
-TweakGatherLoop(ToolsAppCtx *ctx,    // IN
-                gboolean enable)     // IN
+TweakGatherLoopEx(ToolsAppCtx *ctx,       // IN
+                  guint pollInterval)     // IN
 {
-   gint pollInterval = 0;
-
-   if (enable) {
-      pollInterval = APP_INFO_POLL_INTERVAL * 1000;
-
-      /*
-      * Check the config registry for custom poll interval,
-      * converting from seconds to milliseconds.
-      */
-      if (g_key_file_has_key(ctx->config, CONFGROUPNAME_APPINFO,
-                             CONFNAME_APPINFO_POLLINTERVAL, NULL)) {
-         GError *gError = NULL;
-
-         pollInterval = g_key_file_get_integer(ctx->config,
-                                               CONFGROUPNAME_APPINFO,
-                                               CONFNAME_APPINFO_POLLINTERVAL,
-                                               &gError);
-         pollInterval *= 1000;
-
-         if (pollInterval < 0 || gError) {
-            g_warning("%s: Invalid %s.%s value. Using default %us.\n",
-                      __FUNCTION__,
-                      CONFGROUPNAME_APPINFO,
-                      CONFNAME_APPINFO_POLLINTERVAL,
-                      APP_INFO_POLL_INTERVAL);
-            pollInterval = APP_INFO_POLL_INTERVAL * 1000;
-         }
-
-         g_clear_error(&gError);
-      }
-   }
-
    if (gAppInfoTimeoutSource != NULL) {
       /*
-       * If the interval hasn't changed, let's not interfere with the existing
-       * timeout source.
-       */
-      if (pollInterval == gAppInfoPollInterval) {
-         ASSERT(pollInterval);
-         return;
-      }
-
-      /*
-       * Destroy the existing timeout source since the interval has changed.
+       * Destroy the existing timeout source.
        */
-
       g_source_destroy(gAppInfoTimeoutSource);
       gAppInfoTimeoutSource = NULL;
    }
 
-   /*
-    * All checks have passed.  Create a new timeout source and attach it.
-    */
-   gAppInfoPollInterval = pollInterval;
-
-   if (gAppInfoPollInterval) {
-      g_info("%s: New value for %s is %us.\n",
-             __FUNCTION__,
-             CONFNAME_APPINFO_POLLINTERVAL,
-             gAppInfoPollInterval / 1000);
+   if (pollInterval > 0) {
+      if (gAppInfoPollInterval != pollInterval) {
+         g_info("%s: New value for %s is %us.\n",
+                __FUNCTION__,
+                CONFNAME_APPINFO_POLLINTERVAL,
+                pollInterval);
+      }
 
-      gAppInfoTimeoutSource = g_timeout_source_new(gAppInfoPollInterval);
+      gAppInfoTimeoutSource = g_timeout_source_new(pollInterval * 1000);
       VMTOOLSAPP_ATTACH_SOURCE(ctx, gAppInfoTimeoutSource,
                                AppInfoGather, ctx, NULL);
       g_source_unref(gAppInfoTimeoutSource);
-   } else {
+   } else if (gAppInfoPollInterval > 0) {
       g_info("%s: Poll loop for %s disabled.\n",
              __FUNCTION__, CONFNAME_APPINFO_POLLINTERVAL);
       SetGuestInfo(ctx, APP_INFO_GUESTVAR_KEY, "");
    }
+
+   gAppInfoPollInterval = pollInterval;
+}
+
+
+/*
+ *****************************************************************************
+ * TweakGatherLoop --
+ *
+ * Configues the AppInfo Gather poll loop based on the settings in the
+ * tools configuration.
+ *
+ * This function is responsible for creating, manipulating, and resetting a
+ * AppInfo Gather loop timeout source.
+ *
+ * @param[in]     ctx           The application context.
+ *
+ *****************************************************************************
+ */
+
+static void
+TweakGatherLoop(ToolsAppCtx *ctx)    // IN
+{
+   gboolean disabled =
+      VMTools_ConfigGetBoolean(ctx->config,
+                               CONFGROUPNAME_APPINFO,
+                               CONFNAME_APPINFO_DISABLED,
+                               APP_INFO_CONF_DEFAULT_DISABLED_VALUE);
+
+   gint pollInterval = 0;
+
+   if (!disabled) {
+      pollInterval = VMTools_ConfigGetInteger(ctx->config,
+                                              CONFGROUPNAME_APPINFO,
+                                              CONFNAME_APPINFO_POLLINTERVAL,
+                                              APP_INFO_POLL_INTERVAL);
+
+      if (pollInterval < 0) {
+         g_warning("%s: Invalid poll interval %d. Using default %us.\n",
+                   __FUNCTION__, pollInterval, APP_INFO_POLL_INTERVAL);
+         pollInterval = APP_INFO_POLL_INTERVAL;
+      }
+   }
+
+   /*
+    * pollInterval can never be a negative value. Typecasting into
+    * guint should not be a problem.
+    */
+   TweakGatherLoopEx(ctx, (guint) pollInterval);
 }
 
 
@@ -508,7 +523,7 @@ TweakGatherLoop(ToolsAppCtx *ctx,    // IN
  *****************************************************************************
  * AppInfoServerConfReload --
  *
- * @brief Reconfigures the poll loop interval upon config file reload.
+ * Reconfigures the poll loop interval upon config file reload.
  *
  * @param[in]  src     The source object.
  * @param[in]  ctx     The application context.
@@ -522,12 +537,9 @@ AppInfoServerConfReload(gpointer src,       // IN
                         ToolsAppCtx *ctx,   // IN
                         gpointer data)      // IN
 {
-   gboolean disabled =
-      VMTools_ConfigGetBoolean(ctx->config,
-                               CONFGROUPNAME_APPINFO,
-                               CONFNAME_APPINFO_DISABLED,
-                               APP_INFO_CONF_DEFAULT_DISABLED_VALUE);
-   TweakGatherLoop(ctx, !disabled);
+   g_info("%s: Reloading the tools configuration.\n", __FUNCTION__);
+
+   TweakGatherLoop(ctx);
 }
 
 
@@ -538,7 +550,7 @@ AppInfoServerConfReload(gpointer src,       // IN
  * Cleanup internal data on shutdown.
  *
  * @param[in]  src     The source object.
- * @param[in]  ctx     Unused.
+ * @param[in]  ctx     Application context.
  * @param[in]  data    Unused.
  *
  *****************************************************************************
@@ -558,6 +570,66 @@ AppInfoServerShutdown(gpointer src,          // IN
 }
 
 
+/*
+ ******************************************************************************
+ * AppInfoServerReset --
+ *
+ * Callback function that gets called whenever the RPC channel gets reset.
+ * Disables the poll loop and sets a one time poll.
+ *
+ * @param[in]  src      The source object.
+ * @param[in]  ctx      Application context.
+ * @param[in]  data     Unused.
+ *
+ ******************************************************************************
+ */
+
+static void
+AppInfoServerReset(gpointer src,
+                   ToolsAppCtx *ctx,
+                   gpointer data)
+{
+   /*
+    * gAppInfoTimeoutSource is used to figure out if the poll loop is
+    * enabled or not. If the poll loop is disabled, then
+    * gAppInfoTimeoutSource will be set to NULL.
+    */
+   if (gAppInfoTimeoutSource != NULL) {
+      guint interval;
+
+      ASSERT(gAppInfoPollInterval != 0);
+
+#define MIN_APPINFO_INTERVAL 30
+
+      if (gAppInfoPollInterval > MIN_APPINFO_INTERVAL) {
+         GRand *gRand = g_rand_new();
+
+         /*
+          * The RPC channel may get reset due to various conditions like
+          * snapshotting the VM, vmotion the VM, instant cloning of the VM.
+          * In order to avoid potential load spikes in case of instant clones,
+          * randomize the poll interval after a channel reset.
+          */
+
+         interval = g_rand_int_range(gRand,
+                                     MIN_APPINFO_INTERVAL,
+                                     gAppInfoPollInterval);
+         g_rand_free(gRand);
+      } else {
+         interval = gAppInfoPollInterval;
+      }
+
+#undef MIN_APPINFO_INTERVAL
+
+      g_info("%s: Using poll interval: %u.\n", __FUNCTION__, interval);
+
+      TweakGatherLoopEx(ctx, interval);
+   } else {
+      g_debug("%s: Poll loop disabled. Ignoring.\n", __FUNCTION__);
+   }
+}
+
+
 /*
  *****************************************************************************
  * ToolsOnLoad --
@@ -604,7 +676,8 @@ ToolsOnLoad(ToolsAppCtx *ctx)    // IN
    if (ctx->rpc != NULL) {
       ToolsPluginSignalCb sigs[] = {
          { TOOLS_CORE_SIG_CONF_RELOAD, AppInfoServerConfReload, NULL },
-         { TOOLS_CORE_SIG_SHUTDOWN, AppInfoServerShutdown, NULL }
+         { TOOLS_CORE_SIG_SHUTDOWN, AppInfoServerShutdown, NULL },
+         { TOOLS_CORE_SIG_RESET, AppInfoServerReset, NULL }
       };
       ToolsAppReg regs[] = {
          { TOOLS_APP_SIGNALS,
@@ -612,8 +685,6 @@ ToolsOnLoad(ToolsAppCtx *ctx)    // IN
          }
       };
 
-      gboolean disabled = FALSE;
-
       regData.regs = VMTools_WrapArray(regs,
                                        sizeof *regs,
                                        ARRAYSIZE(regs));
@@ -621,15 +692,10 @@ ToolsOnLoad(ToolsAppCtx *ctx)    // IN
       /*
        * Set up the AppInfo gather loop.
        */
-      disabled =
-         VMTools_ConfigGetBoolean(ctx->config,
-                                  CONFGROUPNAME_APPINFO,
-                                  CONFNAME_APPINFO_DISABLED,
-                                  APP_INFO_CONF_DEFAULT_DISABLED_VALUE);
-      TweakGatherLoop(ctx, !disabled);
+      TweakGatherLoop(ctx);
 
       return &regData;
    }
 
    return NULL;
-}
\ No newline at end of file
+}