From 9df3a49445fe12831fd73b5168b15d7a2fb74e8d Mon Sep 17 00:00:00 2001
From: Maas-Maarten Zeeman <mmzeeman@xs4all.nl>
Date: Thu, 28 Nov 2013 19:41:40 +0100
Subject: [PATCH] Use a selective receive, and ignore stale answers. I think
 this fixes #3

---
 c_src/esqlite3_nif.c |  6 +++++-
 src/esqlite3.erl     | 13 +++++++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/c_src/esqlite3_nif.c b/c_src/esqlite3_nif.c
index 5ab5c32..6ac86f4 100644
--- a/c_src/esqlite3_nif.c
+++ b/c_src/esqlite3_nif.c
@@ -71,6 +71,8 @@ typedef struct {
     sqlite3_stmt *stmt;
 } esqlite_command;
 
+ERL_NIF_TERM atom_esqlite3;
+
 static ERL_NIF_TERM 
 make_atom(ErlNifEnv *env, const char *atom_name) 
 {
@@ -570,7 +572,7 @@ push_command(ErlNifEnv *env, esqlite_connection *conn, esqlite_command *cmd) {
 static ERL_NIF_TERM
 make_answer(esqlite_command *cmd, ERL_NIF_TERM answer)
 {
-    return enif_make_tuple2(cmd->env, cmd->ref, answer);
+    return enif_make_tuple3(cmd->env, atom_esqlite3, cmd->ref, answer);
 }
 
 static void *
@@ -919,6 +921,8 @@ on_load(ErlNifEnv* env, void** priv, ERL_NIF_TERM info)
 	    return -1;
     esqlite_statement_type = rt;
 
+    atom_esqlite3 = make_atom(env, "esqlite3");
+
     return 0;
 }
 
diff --git a/src/esqlite3.erl b/src/esqlite3.erl
index 102c663..597accc 100644
--- a/src/esqlite3.erl
+++ b/src/esqlite3.erl
@@ -287,9 +287,18 @@ close({connection, _Ref, Connection}, Timeout) ->
 %% Internal functions
 
 receive_answer(Ref, Timeout) ->
+    Start = os:timestamp(),
     receive 
-        {Ref, Resp} -> Resp;
-        Other -> throw(Other)
+        {esqlite3, Ref, Resp} -> 
+            Resp;
+        {esqlite3, _, _}=StaleAnswer ->
+            error_logger:warning_msg("Esqlite3: Ignoring stale answer ~p~n", [StaleAnswer]),
+            PassedMics = timer:now_diff(os:timestamp(), Start) div 1000,
+            NewTimeout = case Timeout - PassedMics of
+                Passed when Passed < 0 -> 0;
+                TO -> TO
+            end,
+            receive_answer(Ref, NewTimeout)
     after Timeout ->
         throw({error, timeout, Ref})
     end.