Allow for initual burst at full speed

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1770951 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index bed19108d20e43107cf933223d005f78782506c4..ccb724486f3e984fa61872e9046f520890c1d6bf 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,10 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.0
 
+  *) mod_ratelimit: Allow for initial "burst" amount at full speed before
+     throttling: PR 60145 [Andy Valencia <ajv-etradanalhos vsta.org>,
+     Jim Jagielski]
+
   *) event: Allow to use the whole allocated scoreboard (up to ServerLimit
      slots) to avoid scoreboard full errors when some processes are finishing
      gracefully. Also, make gracefully finishing processes close all

diff --git a/docs/log-message-tags/next-number b/docs/log-message-tags/next-number
index 294337bb646b5b52727165e0b0200589c4f82d4b..98233cb68ed41b80058180738d42456f5d7c8fbe 100644 (file)
--- a/docs/log-message-tags/next-number
+++ b/docs/log-message-tags/next-number
@@ -1 +1 @@
-3485
+3486

diff --git a/docs/manual/mod/mod_ratelimit.xml b/docs/manual/mod/mod_ratelimit.xml
index affb2daf26e1f0b1e3ab2a258e1a7b37c1992e99..8adfb8acb343f2fdb04502995035aabff1783672 100644 (file)
--- a/docs/manual/mod/mod_ratelimit.xml
+++ b/docs/manual/mod/mod_ratelimit.xml
@@ -37,11 +37,17 @@ the document to validate. -->
 The connection speed to be simulated is specified, in KiB/s, using the environment
 variable <code>rate-limit</code>.</p>
 
+<p>Optionally, an initial amount of burst data, in KiB, may be
+configured to be passed at full speed before throttling to the
+specified rate limit.  This value is optional, and is set using
+the environment variable <code>rate-initial-burst</code>.</p>
+
 <example><title>Example Configuration</title>
 <highlight language="config">
 &lt;Location "/downloads"&gt;
     SetOutputFilter RATE_LIMIT
     SetEnv rate-limit 400
+    SetEnv rate-initial-burst 512
 &lt;/Location&gt;
 </highlight>
 </example>

diff --git a/modules/filters/mod_ratelimit.c b/modules/filters/mod_ratelimit.c
index a2e9bd0197710ae321edc4e9a51a598601162a39..0f95e80a73e432342c86370e1ee14fe296cf8fa0 100644 (file)
--- a/modules/filters/mod_ratelimit.c
+++ b/modules/filters/mod_ratelimit.c
@@ -35,12 +35,13 @@ typedef struct rl_ctx_t
 {
     int speed;
     int chunk_size;
+    int burst;
     rl_state_e state;
     apr_bucket_brigade *tmpbb;
     apr_bucket_brigade *holdingbb;
 } rl_ctx_t;
 
-#if 0
+#if defined(RLFDEBUG)
 static void brigade_dump(request_rec *r, apr_bucket_brigade *bb)
 {
     apr_bucket *e;
@@ -53,7 +54,7 @@ static void brigade_dump(request_rec *r, apr_bucket_brigade *bb)
 
     }
 }
-#endif
+#endif /* RLFDEBUG */
 
 static apr_status_t
 rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)
@@ -71,10 +72,12 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)
         return APR_ECONNABORTED;
     }
 
+    /* Set up our rl_ctx_t on first use */
     if (ctx == NULL) {
 
         const char *rl = NULL;
         int ratelimit;
+        int burst = 0;
 
         /* no subrequests. */
         if (f->r->main != NULL) {
@@ -82,6 +85,7 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)
             return ap_pass_brigade(f->next, bb);
         }
 
+        /* Configuration: rate limit */
         rl = apr_table_get(f->r->subprocess_env, "rate-limit");
 
         if (rl == NULL) {
@@ -97,11 +101,21 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)
             return ap_pass_brigade(f->next, bb);
         }
 
-        /* first run, init stuff */
+        /* Configuration: optional initial burst */
+        rl = apr_table_get(f->r->subprocess_env, "rate-initial-burst");
+        if (rl != NULL) {
+            burst = atoi(rl) * 1024;
+            if (burst <= 0) {
+                burst = 0;
+            }
+        }
+
+        /* Set up our context */
         ctx = apr_palloc(f->r->pool, sizeof(rl_ctx_t));
         f->ctx = ctx;
         ctx->state = RATE_LIMIT;
         ctx->speed = ratelimit;
+        ctx->burst = burst;
 
         /* calculate how many bytes / interval we want to send */
         /* speed is bytes / second, so, how many  (speed / 1000 % interval) */
@@ -183,7 +197,15 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)
 
                 apr_brigade_length(bb, 1, &len);
 
-                rv = apr_brigade_partition(bb, ctx->chunk_size, &stop_point);
+                /*
+                 * Pull next chunk of data; the initial amount is our
+                 * burst allotment (if any) plus a chunk.  All subsequent
+                 * iterations are just chunks with whatever remaining
+                 * burst amounts we have left (in case not done in the
+                 * first bucket).
+                 */
+                rv = apr_brigade_partition(bb,
+                    ctx->chunk_size + ctx->burst, &stop_point);
                 if (rv != APR_SUCCESS && rv != APR_INCOMPLETE) {
                     ctx->state = RATE_ERROR;
                     ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, f->r, APLOGNO(01456)
@@ -207,15 +229,33 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)
 
                 APR_BRIGADE_INSERT_TAIL(ctx->tmpbb, fb);
 
-#if 0
+                /*
+                 * Adjust the burst amount depending on how much
+                 * we've done up to now.
+                 */
+                if (ctx->burst) {
+                    len = ctx->burst;
+                    apr_brigade_length(ctx->tmpbb, 1, &len);
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, f->r,
+                        APLOGNO(03485) "rl: burst %d; len %"APR_OFF_T_FMT, ctx->burst, len);
+                    if (len < ctx->burst) {
+                        ctx->burst -= len;
+                    }
+                    else {
+                        ctx->burst = 0;
+                    }
+                }
+
+#if defined(RLFDEBUG)
                 brigade_dump(f->r, ctx->tmpbb);
                 brigade_dump(f->r, bb);
-#endif
+#endif /* RLFDEBUG */
 
                 rv = ap_pass_brigade(f->next, ctx->tmpbb);
                 apr_brigade_cleanup(ctx->tmpbb);
 
                 if (rv != APR_SUCCESS) {
+                    /* Most often, user disconnects from stream */
                     ctx->state = RATE_ERROR;
                     ap_log_rerror(APLOG_MARK, APLOG_TRACE1, rv, f->r, APLOGNO(01457)
                                   "rl: brigade pass failed.");