MEDIUM: threads/filters: Add init/deinit callback per thread
Now, it is possible to define init_per_thread and deinit_per_thread callbacks to
deal with ressources allocation for each thread.
This is the filter responsibility to deal with concurrency. This is also the
filter responsibility to know if HAProxy is started with some threads. A good
way to do so is to check "global.nbthread" value. If it is greater than 1, then
_per_thread callbacks will be called.
diff --git a/doc/internals/filters.txt b/doc/internals/filters.txt
index dc55798..1e4d40a 100644
--- a/doc/internals/filters.txt
+++ b/doc/internals/filters.txt
@@ -1,6 +1,6 @@
-----------------------------------------
Filters Guide - version 1.8
- ( Last update: 2016-11-10 )
+ ( Last update: 2017-07-27 )
------------------------------------------
Author : Christopher Faulet
Contact : christopher dot faulet at capflam dot org
@@ -33,6 +33,7 @@
3.1. API Overview
3.2. Defining the filter name and its configuration
3.3. Managing the filter lifecycle
+ 3.3.1. Dealing with threads
3.4. Handling the streams activity
3.5. Analyzing the channels activity
3.6. Filtering the data exchanged
@@ -179,9 +180,11 @@
/*
* Callbacks to manage the filter lifecycle
*/
- int (*init) (struct proxy *p, struct flt_conf *fconf);
- void (*deinit)(struct proxy *p, struct flt_conf *fconf);
- int (*check) (struct proxy *p, struct flt_conf *fconf);
+ int (*init) (struct proxy *p, struct flt_conf *fconf);
+ void (*deinit) (struct proxy *p, struct flt_conf *fconf);
+ int (*check) (struct proxy *p, struct flt_conf *fconf);
+ int (*init_per_thread) (struct proxy *p, struct flt_conf *fconf);
+ void (*deinit_per_thread)(struct proxy *p, struct flt_conf *fconf);
/*
* Stream callbacks
@@ -473,7 +476,7 @@
----------------------------------
Once the configuration parsed and checked, filters are ready to by used. There
-are two callbacks to manage the filter lifecycle:
+are two main callbacks to manage the filter lifecycle:
* 'flt_ops.init': It initializes the filter for a proxy. You may define this
callback if you need to complete your filter configuration.
@@ -514,6 +517,30 @@
document it.
+3.3.1 DEALING WITH THREADS
+--------------------------
+
+When HAProxy is compiled with the threads support and started with more that one
+thread (global.nbthread > 1), then it is possible to manage the filter per
+thread with following callbacks:
+
+ * 'flt_ops.init_per_thread': It initializes the filter for each thread. It
+ works the same way than 'flt_ops.init' but in the
+ context of a thread. This callback is called
+ after the thread creation.
+
+ * 'flt_ops.deinit_per_thread': It cleans up what the init_per_thread callback
+ have done. It is called in the context of a
+ thread, before exiting it.
+
+This is the filter's responsibility to deal with concurrency. check, init and
+deinit callbacks are called on the main thread. All others are called on a
+"worker" thread (not always the same). This is also the filter's responsibility
+to know if HAProxy is started with more than one thread. If it is started with
+one thread (or compiled without the threads support), these callbacks will be
+silently ignored (in this case, global.nbthread will be always equal to one).
+
+
3.4. HANDLING THE STREAMS ACTIVITY
-----------------------------------