bugfix: posted event handler was called after event memory was freed. (#282)

Author: zhuizhuhaomeng

src/ngx_stream_lua_semaphore.c

@@ -476,6 +476,10 @@ ngx_stream_lua_sema_handler(ngx_event_t *ev)
     ngx_queue_t                         *q;
 
     sem = ev->data;
+    ngx_log_debug2(NGX_LOG_DEBUG_STREAM, ngx_cycle->log, 0,
+                   "semaphore handler: wait queue: %sempty, resource count: %d",
+                   ngx_queue_empty(&sem->wait_queue) ? "" : "not ",
+                   sem->resource_count);
 
     while (!ngx_queue_empty(&sem->wait_queue) && sem->resource_count > 0) {
 
@@ -572,6 +576,10 @@ ngx_stream_lua_ffi_sema_gc(ngx_stream_lua_sema_t *sem)
                       "destroyed", sem);
     }
 
+    if (sem->sem_event.posted) {
+        ngx_delete_posted_event(&sem->sem_event);
+    }
+
     ngx_stream_lua_free_sema(sem);
 }
 

t/154-semaphore.t

@@ -0,0 +1,134 @@
+use Test::Nginx::Socket::Lua::Stream;
+
+repeat_each(2);
+
+plan tests => repeat_each() * (blocks() * 3) + 1;
+
+log_level("debug");
+no_long_string();
+#no_diff();
+run_tests();
+
+__DATA__
+
+=== TEST 1: timer + shutdown error log
+--- stream_server_config
+        content_by_lua_block {
+            local function test(pre)
+
+                local semaphore = require "ngx.semaphore"
+                local sem = semaphore.new()
+
+                local function sem_wait()
+
+                    local ok, err = sem:wait(10)
+                    if not ok then
+                        ngx.log(ngx.ERR, "err: ", err)
+                    else
+                        ngx.log(ngx.info, "wait success")
+                    end
+                end
+
+                while not ngx.worker.exiting() do
+                    local co = ngx.thread.spawn(sem_wait)
+                    ngx.thread.wait(co)
+                end
+            end
+
+            local ok, err = ngx.timer.at(0, test)
+            ngx.log(ngx.INFO, "hello, world")
+            ngx.say("time: ", ok)
+        }
+--- request
+GET /t
+--- stream_response_like eval
+time: 1
+--- grep_error_log eval: qr/hello, world|semaphore gc wait queue is not empty/
+--- grep_error_log_out
+hello, world
+--- shutdown_error_log
+--- no_shutdown_error_log
+semaphore gc wait queue is not empty
+
+
+
+=== TEST 2: timer + shutdown error log (lua code cache off)
+FIXME: this test case leaks memory.
+--- stream_server_config
+        lua_code_cache off;
+        content_by_lua_block {
+            local function test(pre)
+
+                local semaphore = require "ngx.semaphore"
+                local sem = semaphore.new()
+
+                local function sem_wait()
+
+                    local ok, err = sem:wait(10)
+                    if not ok then
+                        ngx.log(ngx.ERR, "err: ", err)
+                    else
+                        ngx.log(ngx.ERR, "wait success")
+                    end
+                end
+
+                while not ngx.worker.exiting() do
+                    local co = ngx.thread.spawn(sem_wait)
+                    ngx.thread.wait(co)
+                end
+            end
+
+            local ok, err = ngx.timer.at(0, test)
+            ngx.log(ngx.ERR, "hello, world")
+            ngx.say("time: ", ok)
+        }
+--- request
+GET /test
+--- stream_response_like eval
+time: 1
+--- grep_error_log eval: qr/hello, world|semaphore gc wait queue is not empty/
+--- grep_error_log_out
+hello, world
+--- shutdown_error_log
+--- no_shutdown_error_log
+semaphore gc wait queue is not empty
+--- SKIP
+
+
+
+=== TEST 3: exit before post_handler was called
+If gc is called before the ngx_http_lua_sema_handler and free the sema memory
+ngx_http_lua_sema_handler would use the freed memory.
+--- stream_server_config
+        content_by_lua_block {
+            local semaphore = require "ngx.semaphore"
+            local sem = semaphore.new()
+
+            local function sem_wait()
+                ngx.log(ngx.INFO, "ngx.sem wait start")
+                local ok, err = sem:wait(10)
+                if not ok then
+                    ngx.log(ngx.ERR, "ngx.sem wait err: ", err)
+                else
+                    ngx.log(ngx.INFO, "ngx.sem wait success")
+                end
+            end
+            local co = ngx.thread.spawn(sem_wait)
+            ngx.log(ngx.INFO, "ngx.sem post start")
+            sem:post()
+            ngx.log(ngx.INFO, "ngx.sem post end")
+            ngx.say("hello")
+            ngx.exit(200)
+            ngx.say("not reach here")
+        }
+--- request
+GET /t
+--- stream_response_like
+hello
+--- grep_error_log eval: qr/(ngx.sem .*?,|close stream connection|semaphore handler: wait queue: empty, resource count: 1)/
+--- grep_error_log_out
+ngx.sem wait start,
+ngx.sem post start,
+ngx.sem post end,
+close stream connection
+semaphore handler: wait queue: empty, resource count: 1