Allow users to replace allocator and handle OOM everywhere. (#800)

* Adds an indirection to every allocation/deallocation to allow users to 
  plug in ones of their choosing (use custom functions, jemalloc, etc).

* Gracefully handle OOM everywhere in hiredis.  This should make it possible
  for users of the library to have more flexibility in how they handle such situations.

* Changes `redisReaderTask->elements` from an `int` to a `long long` to prevent
  a possible overflow when transferring the task elements into a `redisReply`.

* Adds a configurable `max elements` member to `redisReader` that defaults to
  2^32 - 1.  This can be set to "unlimited" by setting the value to zero.

1 files changed, 4 insertions, 1 deletions

diff --git a/adapters/ae.h b/adapters/ae.h
index 0393992..660d82e 100644
--- a/adapters/ae.h
+++ b/adapters/ae.h
@@ -96,7 +96,7 @@ static void redisAeCleanup(void *privdata) {
     redisAeEvents *e = (redisAeEvents*)privdata;
     redisAeDelRead(privdata);
     redisAeDelWrite(privdata);
-    free(e);
+    hi_free(e);
 }
 
 static int redisAeAttach(aeEventLoop *loop, redisAsyncContext *ac) {
@@ -109,6 +109,9 @@ static int redisAeAttach(aeEventLoop *loop, redisAsyncContext *ac) {
 
     /* Create container for context and r/w events */
     e = (redisAeEvents*)hi_malloc(sizeof(*e));
+    if (e == NULL)
+        return REDIS_ERR;
+
     e->context = ac;
     e->loop = loop;
     e->fd = c->fd;