From 95d8a28453b75af80832fc897f0f0a83f73f5805 Mon Sep 17 00:00:00 2001
From: Gregory Burd <greg@basho.com>
Date: Thu, 18 Apr 2013 13:36:24 -0400
Subject: [PATCH] Remove unused num_contexts count.  Cleanup the session/cursor
 cache init process.

---
 c_src/wterl.c | 40 ++++++++++++++++++----------------------
 src/wterl.erl |  2 +-
 2 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/c_src/wterl.c b/c_src/wterl.c
index fbdb27f..4a8992c 100644
--- a/c_src/wterl.c
+++ b/c_src/wterl.c
@@ -71,7 +71,6 @@ typedef struct {
 typedef struct {
     WT_CONNECTION *conn;
     const char *session_config;
-    unsigned int num_contexts;
     ErlNifMutex *contexts_mutex;
     WterlCtx contexts[ASYNC_NIF_MAX_WORKERS];
 } WterlConnHandle;
@@ -108,24 +107,17 @@ ASYNC_NIF_INIT(wterl);
  *
  */
 static int
-__create_new_session_cache(WterlConnHandle *conn_handle, WterlCtx *ctx)
+__init_session_and_cursor_cache(WterlConnHandle *conn_handle, WterlCtx *ctx)
 {
     /* Create a context for this worker thread to reuse. */
-    enif_mutex_lock(conn_handle->contexts_mutex);
-    if (ctx->session != NULL) {
-        enif_mutex_unlock(conn_handle->contexts_mutex);
-        return 0;
-    }
-
     WT_CONNECTION *conn = conn_handle->conn;
     int rc = conn->open_session(conn, NULL, conn_handle->session_config, &ctx->session);
     if (rc != 0) {
+        ctx->session = NULL;
         enif_mutex_unlock(conn_handle->contexts_mutex);
         return rc;
     }
     ctx->cursors = kh_init(cursors);
-    conn_handle->num_contexts++;
-    enif_mutex_unlock(conn_handle->contexts_mutex);
 
     return 0;
 }
@@ -139,9 +131,11 @@ __session_for(WterlConnHandle *conn_handle, unsigned int worker_id, WT_SESSION *
     WterlCtx *ctx = &conn_handle->contexts[worker_id];
     int rc = 0;
 
-    if (ctx->session == NULL)
-        rc = __create_new_session_cache(conn_handle, ctx);
-
+    if (ctx->session == NULL) {
+        enif_mutex_lock(conn_handle->contexts_mutex);
+        rc = __init_session_and_cursor_cache(conn_handle, ctx);
+        enif_mutex_unlock(conn_handle->contexts_mutex);
+    }
     *session = ctx->session;
     return rc;
 }
@@ -155,9 +149,10 @@ void
 __close_all_sessions(WterlConnHandle *conn_handle)
 {
     int i;
+
     for (i = 0; i < ASYNC_NIF_MAX_WORKERS; i++) {
         WterlCtx *ctx = &conn_handle->contexts[i];
-        if (ctx->session) {
+        if (ctx->session != NULL) {
             WT_SESSION *session = ctx->session;
             khash_t(cursors) *h = ctx->cursors;
             khiter_t itr;
@@ -176,7 +171,6 @@ __close_all_sessions(WterlConnHandle *conn_handle)
             ctx->session = NULL;
         }
     }
-    conn_handle->num_contexts = 0;
 }
 
 /**
@@ -188,9 +182,10 @@ void
 __close_cursors_on(WterlConnHandle *conn_handle, const char *uri)
 {
     int i;
+
     for (i = 0; i < ASYNC_NIF_MAX_WORKERS; i++) {
         WterlCtx *ctx = &conn_handle->contexts[i];
-        if (ctx->session) {
+        if (ctx->session != NULL) {
             khash_t(cursors) *h = ctx->cursors;
             khiter_t itr = kh_get(cursors, h, (char *)uri);
             if (itr != kh_end(h)) {
@@ -218,8 +213,11 @@ __retain_cursor(WterlConnHandle *conn_handle, unsigned int worker_id, const char
     khiter_t itr;
     int rc;
 
-    if (ctx->session == NULL)
-        __create_new_session_cache(conn_handle, ctx); // TODO: check return value
+    if (ctx->session == NULL) {
+        enif_mutex_lock(conn_handle->contexts_mutex);
+        __init_session_and_cursor_cache(conn_handle, ctx); // TODO: check return value
+        enif_mutex_unlock(conn_handle->contexts_mutex);
+    }
 
     h = ctx->cursors;
     itr = kh_get(cursors, h, (char *)uri);
@@ -245,7 +243,6 @@ __retain_cursor(WterlConnHandle *conn_handle, unsigned int worker_id, const char
         memcpy(key, uri, 128);
         int itr_status;
         itr = kh_put(cursors, h, key, &itr_status);
-        //assert(itr != kh_end());
 	kh_value(h, itr) = *cursor;
         enif_mutex_unlock(conn_handle->contexts_mutex);
     }
@@ -349,7 +346,6 @@ ASYNC_NIF_DECL(
       conn_handle->contexts_mutex = enif_mutex_create(NULL);
       enif_mutex_lock(conn_handle->contexts_mutex);
       conn_handle->conn = conn;
-      conn_handle->num_contexts = 0;
       memset(conn_handle->contexts, 0, sizeof(WterlCtx) * ASYNC_NIF_MAX_WORKERS);
       ERL_NIF_TERM result = enif_make_resource(env, conn_handle);
 
@@ -420,9 +416,9 @@ ASYNC_NIF_DECL(
         kh_value(h, itr) = NULL;
     }
     enif_mutex_unlock(args->priv->conns_mutex);
-
+    // TODO: dtor? enif_mutex_destroy(args->conn_handle->contexts_mutex);
     enif_mutex_unlock(args->conn_handle->contexts_mutex);
-    enif_mutex_destroy(args->conn_handle->contexts_mutex);
+
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
   },
   { // post
diff --git a/src/wterl.erl b/src/wterl.erl
index b7c3900..f6da109 100644
--- a/src/wterl.erl
+++ b/src/wterl.erl
@@ -516,7 +516,7 @@ config_to_bin([{Key, Value} | Rest], Acc) ->
 -define(TEST_DATA_DIR, "test/wterl.basic").
 
 open_test_conn(DataDir) ->
-    open_test_conn(DataDir, [{create,true},{cache_size,"100MB"}]).
+    open_test_conn(DataDir, [{create,true},{cache_size,"100MB"},{session_max, 8192}]).
 open_test_conn(DataDir, OpenConfig) ->
     {ok, CWD} = file:get_cwd(),
     rmdir:path(filename:join([CWD, DataDir])), %?cmd("rm -rf " ++ filename:join([CWD, DataDir])),