From c560c645e9d79df607c829de64b86d0513b8a08c Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Mon, 16 Nov 2015 13:58:17 +0100
Subject: [PATCH] Lua debugger: trace command implemented.

---
 src/scripting.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/scripting.c b/src/scripting.c
index 8c345192..59a0d7a3 100644
--- a/src/scripting.c
+++ b/src/scripting.c
@@ -2145,6 +2145,26 @@ void ldbRedis(lua_State *lua, sds *argv, int argc) {
     lua_pop(lua,2);             /* Discard the result and clean the stack. */
 }
 
+/* Implements "trace" command of the Lua debugger. It just prints a backtrace
+ * querying Lua starting from the current callframe back to the outer one. */
+void ldbTrace(lua_State *lua) {
+    lua_Debug ar;
+    int level = 0;
+
+    while(lua_getstack(lua,level,&ar)) {
+        lua_getinfo(lua,"Snl",&ar);
+        if(strstr(ar.short_src,"user_script") == NULL) continue;
+        ldbLog(sdscatprintf(sdsempty(),"%s %s:",
+            (level == 0) ? "In" : "From",
+            ar.name ? ar.name : "top level"));
+        ldbLogSourceLine(ar.currentline);
+        level++;
+    }
+    if (level == 0) {
+        ldbLog(sdsnew("<error> Can't retrieve Lua stack."));
+    }
+}
+
 /* Read debugging commands from client. */
 void ldbRepl(lua_State *lua) {
     sds *argv;
@@ -2190,6 +2210,7 @@ ldbLog(sdsnew("[b]reak              Show all breakpoints."));
 ldbLog(sdsnew("[b]reak <line>       Add a breakpoint to the specified line."));
 ldbLog(sdsnew("[b]reak -<line>      Remove breakpoint from the specified line."));
 ldbLog(sdsnew("[b]reak 0            Remove all breakpoints."));
+ldbLog(sdsnew("[t]race              Show a backtrace."));
 ldbLog(sdsnew("[e]eval <code>       Execute some Lua code (in a different callframe)."));
 ldbLog(sdsnew("[r]edis <cmd>        Execute a Redis command."));
 ldbLog(sdsnew("[a]abort             Stop the execution of the script. In sync"));
@@ -2206,6 +2227,9 @@ ldbLog(sdsnew("                     in the next line of code."));
             break;
         } else if (!strcasecmp(argv[0],"c") || !strcasecmp(argv[0],"continue")){
             break;
+        } else if (!strcasecmp(argv[0],"t") || !strcasecmp(argv[0],"trace")) {
+            ldbTrace(lua);
+            ldbSendLogs();
         } else if (!strcasecmp(argv[0],"b") || !strcasecmp(argv[0],"break")) {
             ldbBreak(argv,argc);
             ldbSendLogs();