CDRIVER-789 remove topology scanner's "seen" list

Author: ajdavis

src/mongoc/mongoc-host-list.c

@@ -17,23 +17,6 @@
 #include "mongoc-host-list.h"
 #include "mongoc-util-private.h"
 
-/*
- *--------------------------------------------------------------------------
- *
- * mongoc_host_list_new --
- *
- *       Empty new host list.
- *
- * Side effects:
- *       None.
- *
- *--------------------------------------------------------------------------
- */
-mongoc_host_list_t *
-mongoc_host_list_new (void)
-{
-   return (mongoc_host_list_t *) bson_malloc0 (sizeof (mongoc_host_list_t));
-}
 
 /*
  *--------------------------------------------------------------------------
@@ -57,95 +40,6 @@ mongoc_host_list_equal (const mongoc_host_list_t *host_a,
 }
 
 
-/*
- *--------------------------------------------------------------------------
- *
- * mongoc_host_list_find --
- *
- *       Search for an equal mongoc_host_list_t in a list of them.
- *
- * Returns:
- *       Pointer to an entry in "list", or NULL.
- *
- * Side effects:
- *       None.
- *
- *--------------------------------------------------------------------------
- */
-const mongoc_host_list_t *
-mongoc_host_list_find (const mongoc_host_list_t *list,
-                       const mongoc_host_list_t *needle)
-{
-   while (list) {
-      if (mongoc_host_list_equal (list, needle)) {
-         return list;
-      }
-
-      list = list->next;
-   }
-
-   return NULL;
-}
-
-
-/*
- *--------------------------------------------------------------------------
- *
- * mongoc_host_list_count --
- *
- *       Return number of items in the host list.
- *
- * Returns:
- *       0 or greater.
- *
- * Side effects:
- *       None.
- *
- *--------------------------------------------------------------------------
- */
-size_t
-mongoc_host_list_count (const mongoc_host_list_t *list)
-{
-   size_t count = 0;
-
-   while (list) {
-      count++;
-      list = list->next;
-   }
-
-   return count;
-}
-
-
-/*
- *--------------------------------------------------------------------------
- *
- * host_list_copy --
- *
- *       Make a copy of "host" with next set to "next".
- *
- * Returns:
- *       New copy.
- *
- * Side effects:
- *       None.
- *
- *--------------------------------------------------------------------------
- */
-mongoc_host_list_t *
-mongoc_host_list_copy (const mongoc_host_list_t *host,
-                       mongoc_host_list_t *next)
-{
-   mongoc_host_list_t *copy;
-
-   copy = mongoc_host_list_new ();
-   memcpy ((void *) copy, (void *) host, sizeof (mongoc_host_list_t));
-   copy->next = next;
-
-   return copy;
-}
-
-
 /*
  *--------------------------------------------------------------------------
  *

src/mongoc/mongoc-host-list.h

@@ -51,19 +51,9 @@ struct _mongoc_host_list_t
    void               *padding [4];
 };
 
-mongoc_host_list_t *mongoc_host_list_new (void);
-
 bool mongoc_host_list_equal (const mongoc_host_list_t *host_a,
                              const mongoc_host_list_t *host_b);
 
-const mongoc_host_list_t *mongoc_host_list_find (const mongoc_host_list_t *list,
-                                                 const mongoc_host_list_t *needle);
-
-size_t mongoc_host_list_count (const mongoc_host_list_t *list);
-
-mongoc_host_list_t *mongoc_host_list_copy (const mongoc_host_list_t *host,
-                                           mongoc_host_list_t *next);
-
 void mongoc_host_list_destroy_all (mongoc_host_list_t *host);
 
 BSON_END_DECLS

src/mongoc/mongoc-topology-scanner-private.h

@@ -71,7 +71,6 @@ typedef struct mongoc_topology_scanner
    mongoc_async_cmd_setup_t        setup;
    mongoc_stream_initiator_t       initiator;
    void                           *initiator_context;
-   mongoc_host_list_t             *seen;
 
 #ifdef MONGOC_ENABLE_SSL
    mongoc_ssl_opt_t *ssl_opts;
@@ -120,6 +119,10 @@ mongoc_topology_scanner_node_t *
 mongoc_topology_scanner_get_node (mongoc_topology_scanner_t *ts,
                                   uint32_t                   id);
 
+bool
+mongoc_topology_scanner_has_node_for_host (mongoc_topology_scanner_t *ts,
+                                           mongoc_host_list_t        *host);
+
 void
 mongoc_topology_scanner_set_stream_initiator (mongoc_topology_scanner_t *ts,
                                               mongoc_stream_initiator_t  si,

src/mongoc/mongoc-topology-scanner.c

@@ -92,8 +92,6 @@ mongoc_topology_scanner_destroy (mongoc_topology_scanner_t *ts)
    mongoc_async_destroy (ts->async);
    bson_destroy (&ts->ismaster_cmd);
 
-   mongoc_host_list_destroy_all (ts->seen);
-
    bson_free (ts);
 }
 
@@ -104,15 +102,6 @@ mongoc_topology_scanner_add (mongoc_topology_scanner_t *ts,
 {
    mongoc_topology_scanner_node_t *node;
 
-   if (mongoc_host_list_find (ts->seen, host)) {
-      /* already seen this host -- avoid pathological case like two primaries
-       * pointing at each other, each invalidating itself and trying to add the
-       * other on each check within the same blocking scan, see
-       * test_topology_scanner_oscillate
-       */
-      return NULL;
-   }
-
    node = (mongoc_topology_scanner_node_t *) bson_malloc0 (sizeof (*node));
 
    memcpy (&node->host, host, sizeof (*host));
@@ -123,8 +112,6 @@ mongoc_topology_scanner_add (mongoc_topology_scanner_t *ts,
 
    DL_APPEND(ts->nodes, node);
 
-   ts->seen = mongoc_host_list_copy (host, ts->seen);
-
    return node;
 }
 
@@ -221,6 +208,31 @@ mongoc_topology_scanner_get_node (mongoc_topology_scanner_t *ts,
    return NULL;
 }
 
+/*
+ *--------------------------------------------------------------------------
+ *
+ * mongoc_topology_scanner_has_node_for_host --
+ *
+ *      Whether the scanner has a node for the given host and port.
+ *
+ *--------------------------------------------------------------------------
+ */
+bool
+mongoc_topology_scanner_has_node_for_host (mongoc_topology_scanner_t *ts,
+                                           mongoc_host_list_t        *host)
+{
+   mongoc_topology_scanner_node_t *ele, *tmp;
+
+   DL_FOREACH_SAFE (ts->nodes, ele, tmp)
+   {
+      if (mongoc_host_list_equal (&ele->host, host)) {
+         return true;
+      }
+   }
+
+   return false;
+}
+
 /*
  *-----------------------------------------------------------------------
  *
@@ -549,9 +561,6 @@ mongoc_topology_scanner_reset (mongoc_topology_scanner_t *ts)
          mongoc_topology_scanner_node_destroy (node, true);
       }
    }
-
-   mongoc_host_list_destroy_all (ts->seen);
-   ts->seen = NULL;
 }
 
 void

src/mongoc/mongoc-topology.c

@@ -38,7 +38,10 @@ _mongoc_topology_reconcile_add_nodes (void *item,
    mongoc_topology_t *topology = (mongoc_topology_t *)ctx;
    mongoc_topology_scanner_t *scanner = topology->scanner;
 
-   if (! mongoc_topology_scanner_get_node (scanner, sd->id)) {
+   /* quickly search by id, then check if a node for this host was retired in
+    * this scan. */
+   if (! mongoc_topology_scanner_get_node (scanner, sd->id) &&
+       ! mongoc_topology_scanner_has_node_for_host (scanner, &sd->host)) {
       mongoc_topology_scanner_add_and_scan (scanner, &sd->host, sd->id,
                                             topology->connect_timeout_msec);
    }

tests/test-mongoc-topology-reconcile.c

@@ -176,7 +176,7 @@ _test_topology_reconcile_rs (bool pooled)
     */
    RS_RESPONSE_TO_ISMASTER (server0, true, true, server0);  /* server1 absent */
 
-   assert (selects_server (client, tag_read_prefs, server1));
+   assert (selects_server (client, tag_read_prefs, server0));
    assert (!client->topology->stale);
 
    if (!pooled) {

tests/test-mongoc-topology-scanner.c

@@ -183,14 +183,12 @@ test_topology_scanner_discovery ()
 
    /* a single scan discovers *and* checks the secondary */
    AWAIT (scanner->async->ncmds == 1);
-   ASSERT_CMPINT (1, ==, (int) mongoc_host_list_count (scanner->seen));
    request = mock_server_receives_ismaster (primary);
    mock_server_replies_simple (request, primary_response);
    request_destroy (request);
 
    /* let client process that response */
    _mongoc_usleep (250 * 1000);
-   ASSERT_CMPINT (2, ==, (int) mongoc_host_list_count (scanner->seen));
 
    /* a check of the secondary is scheduled in this scan */
    AWAIT (scanner->async->ncmds == 1);
@@ -205,9 +203,6 @@ test_topology_scanner_discovery ()
    ASSERT_CMPSTR (sd->host.host_and_port,
                   mock_server_get_host_and_port (secondary));
 
-   /* "seen" is reset */
-   ASSERT_CMPINT (0, ==, (int) mongoc_host_list_count (scanner->seen));
-
    mongoc_server_description_destroy (sd);
    future_destroy (future);
    request_destroy (request);
@@ -288,9 +283,6 @@ test_topology_scanner_oscillate ()
    assert (!future_get_mongoc_server_description_ptr (future));
    assert (scanner->async->ncmds == 0);
 
-   /* "seen" is reset */
-   ASSERT_CMPINT (0, ==, (int) mongoc_host_list_count (scanner->seen));
-
    future_destroy (future);
    request_destroy (request);
    mongoc_read_prefs_destroy (primary_pref);