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Posted to cvs@httpd.apache.org by ji...@apache.org on 2007/11/13 22:55:10 UTC

svn commit: r594659 - /httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c

Author: jim
Date: Tue Nov 13 13:55:05 2007
New Revision: 594659

URL: http://svn.apache.org/viewvc?rev=594659&view=rev
Log:
Add extremely butt-ugly sub-mod that exists simply to show how
to use providers in sub-mods to extend lbmethods in mod_proxy...

Added:
    httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c   (with props)

Added: httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c?rev=594659&view=auto
==============================================================================
--- httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c (added)
+++ httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c Tue Nov 13 13:55:05 2007
@@ -0,0 +1,122 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Round Robin lbmethod module for Apache proxy */
+
+/* NOTE: This is designed simply to provide some info on how to create
+         extra lbmethods via sub-modules... This code is ugly
+         and needs work to actually do round-robin "right"
+         but that is left as an exercise for the reader */
+
+#define CORE_PRIVATE
+
+#include "mod_proxy.h"
+#include "scoreboard.h"
+#include "ap_mpm.h"
+#include "apr_version.h"
+#include "apr_hooks.h"
+
+#if APR_HAVE_UNISTD_H
+#include <unistd.h> /* for getpid() */
+#endif
+
+module AP_MODULE_DECLARE_DATA proxy_balancer_rr_module;
+
+typedef struct {
+    int index;
+} rr_data ;
+
+/*
+ */
+static proxy_worker *find_best_roundrobin(proxy_balancer *balancer,
+                                         request_rec *r)
+{
+    int i;
+    proxy_worker *worker;
+    proxy_worker *mycandidate = NULL;
+    int checking_standby;
+    int checked_standby;
+    rr_data *ctx;
+
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                 "proxy: Entering roundrobin for BALANCER %s (%d)",
+                 balancer->name, (int)getpid());
+    
+    /* The index of the candidate last chosen is stored in ctx->index */
+    if (!balancer->context) {
+        /* UGLY */
+        ctx = apr_pcalloc(r->server->process->pconf, sizeof(rr_data));
+        balancer->context = (void *)ctx;
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                 "proxy: Creating roundrobin ctx for BALANCER %s (%d)",
+                 balancer->name, (int)getpid());
+    } else {
+        ctx = (rr_data *)balancer->context;
+    }
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                 "proxy: roundrobin index: %d (%d)",
+                 ctx->index, (int)getpid());
+
+    do {
+        checking_standby = checked_standby = 0;
+        while (!mycandidate && !checked_standby) {
+            worker = (proxy_worker *)balancer->workers->elts;
+
+            for (i = 0; i < balancer->workers->nelts; i++, worker++) {
+                if (i < ctx->index)
+                    continue;
+                if ( (checking_standby ? !PROXY_WORKER_IS_STANDBY(worker) : PROXY_WORKER_IS_STANDBY(worker)) )
+                    continue;
+                if (!PROXY_WORKER_IS_USABLE(worker))
+                    ap_proxy_retry_worker("BALANCER", worker, r->server);
+                if (PROXY_WORKER_IS_USABLE(worker)) {
+                    mycandidate = worker;
+                    break;
+                }
+            }
+            checked_standby = checking_standby++;
+        }
+    } while (!mycandidate);
+
+    ctx->index += 1;
+    if (ctx->index >= balancer->workers->nelts) {
+        ctx->index = 0;
+    }
+    return mycandidate;
+}
+
+static const proxy_balancer_method roundrobin =
+{
+    "roundrobin",
+    &find_best_roundrobin,
+    NULL
+};
+
+
+static void ap_proxy_rr_register_hook(apr_pool_t *p)
+{
+    ap_register_provider(p, PROXY_LBMETHOD, "roundrobin", "0", &roundrobin);
+}
+
+module AP_MODULE_DECLARE_DATA proxy_balancer_rr_module = {
+    STANDARD20_MODULE_STUFF,
+    NULL,       /* create per-directory config structure */
+    NULL,       /* merge per-directory config structures */
+    NULL,       /* create per-server config structure */
+    NULL,       /* merge per-server config structures */
+    NULL,       /* command apr_table_t */
+    ap_proxy_rr_register_hook /* register hooks */
+};

Propchange: httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c
------------------------------------------------------------------------------
    svn:eol-style = native

Re: svn commit: r594659 - /httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c

Posted by Jim Jagielski <ji...@jaguNET.com>.

On Nov 13, 2007, at 5:14 PM, Jim Jagielski wrote:

>
> On Nov 13, 2007, at 5:11 PM, Ruediger Pluem wrote:
>
>>
>>
>> On 11/13/2007 10:55 PM, jim@apache.org wrote:
>>> Author: jim
>>
>> Isn't this an endless loop if all workers (standby *and* not  
>> standby) are in error mode?
>> I guess it is reasonable to return NULL in this case and let  
>> mod_proxy_balancer handle
>> this (which it actually does in find_best_worker.
>>
>
> Most likely... yeah :)... I'm sure there are other nasty things in  
> there
> as well
>

And there are... ;)

Re: svn commit: r594659 - /httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c

Posted by Jim Jagielski <ji...@jaguNET.com>.

On Nov 13, 2007, at 5:11 PM, Ruediger Pluem wrote:

>
>
> On 11/13/2007 10:55 PM, jim@apache.org wrote:
>> Author: jim
>
> Isn't this an endless loop if all workers (standby *and* not  
> standby) are in error mode?
> I guess it is reasonable to return NULL in this case and let  
> mod_proxy_balancer handle
> this (which it actually does in find_best_worker.
>

Most likely... yeah :)... I'm sure there are other nasty things in there
as well

Re: svn commit: r594659 - /httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c

Posted by Ruediger Pluem <rp...@apache.org>.


On 11/13/2007 10:55 PM, jim@apache.org wrote:
> Author: jim
> Date: Tue Nov 13 13:55:05 2007
> New Revision: 594659
> 
> URL: http://svn.apache.org/viewvc?rev=594659&view=rev
> Log:
> Add extremely butt-ugly sub-mod that exists simply to show how
> to use providers in sub-mods to extend lbmethods in mod_proxy...
> 
> Added:
>     httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c   (with props)
> 
> Added: httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c
> URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c?rev=594659&view=auto
> ==============================================================================
> --- httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c (added)
> +++ httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c Tue Nov 13 13:55:05 2007

> +static proxy_worker *find_best_roundrobin(proxy_balancer *balancer,
> +                                         request_rec *r)
> +{
> +    int i;
> +    proxy_worker *worker;
> +    proxy_worker *mycandidate = NULL;
> +    int checking_standby;
> +    int checked_standby;
> +    rr_data *ctx;
> +
> +    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
> +                 "proxy: Entering roundrobin for BALANCER %s (%d)",
> +                 balancer->name, (int)getpid());
> +    
> +    /* The index of the candidate last chosen is stored in ctx->index */
> +    if (!balancer->context) {
> +        /* UGLY */
> +        ctx = apr_pcalloc(r->server->process->pconf, sizeof(rr_data));
> +        balancer->context = (void *)ctx;
> +        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
> +                 "proxy: Creating roundrobin ctx for BALANCER %s (%d)",
> +                 balancer->name, (int)getpid());
> +    } else {
> +        ctx = (rr_data *)balancer->context;
> +    }
> +    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
> +                 "proxy: roundrobin index: %d (%d)",
> +                 ctx->index, (int)getpid());
> +
> +    do {
> +        checking_standby = checked_standby = 0;
> +        while (!mycandidate && !checked_standby) {
> +            worker = (proxy_worker *)balancer->workers->elts;
> +
> +            for (i = 0; i < balancer->workers->nelts; i++, worker++) {
> +                if (i < ctx->index)
> +                    continue;
> +                if ( (checking_standby ? !PROXY_WORKER_IS_STANDBY(worker) : PROXY_WORKER_IS_STANDBY(worker)) )
> +                    continue;
> +                if (!PROXY_WORKER_IS_USABLE(worker))
> +                    ap_proxy_retry_worker("BALANCER", worker, r->server);
> +                if (PROXY_WORKER_IS_USABLE(worker)) {
> +                    mycandidate = worker;
> +                    break;
> +                }
> +            }
> +            checked_standby = checking_standby++;
> +        }
> +    } while (!mycandidate);

Isn't this an endless loop if all workers (standby *and* not standby) are in error mode?
I guess it is reasonable to return NULL in this case and let mod_proxy_balancer handle
this (which it actually does in find_best_worker.

Regards

Rüdiger

Re: svn commit: r594659 - /httpd/httpd/trunk/modules/proxy/mod_lbmethod_rr.c

Posted by Jim Jagielski <ji...@jaguNET.com>.

On Nov 14, 2007, at 4:37 AM, Paul Querna wrote:

> jim@apache.org wrote:
>> Author: jim
>> Date: Tue Nov 13 13:55:05 2007
>> New Revision: 594659
>>
>> URL: http://svn.apache.org/viewvc?rev=594659&view=rev
>> Log:
>> Add extremely butt-ugly sub-mod that exists simply to show how
>> to use providers in sub-mods to extend lbmethods in mod_proxy...
> .....
>> +
>> +/* Round Robin lbmethod module for Apache proxy */
>> +
>> +/* NOTE: This is designed simply to provide some info on how to  
>> create
>> +         extra lbmethods via sub-modules... This code is ugly
>> +         and needs work to actually do round-robin "right"
>> +         but that is left as an exercise for the reader */
>> +
>> +#define CORE_PRIVATE
>
> boooo.
>
> does it really need CORE_PRIVATE??
>

Nope... it doesn't...