new file mode 100644
--- /dev/null
+++ b/src/http/ngx_http_write_filter.c
@@ -0,0 +1,166 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+#include <ngx_http.h>
+
+
+typedef struct {
+    ngx_chain_t  *out;
+} ngx_http_write_filter_ctx_t;
+
+
+static ngx_int_t ngx_http_write_filter_init(ngx_cycle_t *cycle);
+
+
+ngx_http_module_t  ngx_http_write_filter_module_ctx = {
+    NULL,                                  /* pre conf */
+
+    NULL,                                  /* create main configuration */
+    NULL,                                  /* init main configuration */
+
+    NULL,                                  /* create server configuration */
+    NULL,                                  /* merge server configuration */
+
+    NULL,                                  /* create location configuration */
+    NULL,                                  /* merge location configuration */
+};
+
+
+ngx_module_t  ngx_http_write_filter_module = {
+    NGX_MODULE,
+    &ngx_http_write_filter_module_ctx,     /* module context */
+    NULL,                                  /* module directives */
+    NGX_HTTP_MODULE,                       /* module type */
+    ngx_http_write_filter_init,            /* init module */
+    NULL                                   /* init process */
+};
+
+
+ngx_int_t ngx_http_write_filter(ngx_http_request_t *r, ngx_chain_t *in)
+{
+    int                           last;
+    off_t                         size, flush, sent;
+    ngx_chain_t                  *cl, *ln, **ll, *chain;
+    ngx_connection_t             *c;
+    ngx_http_core_loc_conf_t     *clcf;
+    ngx_http_write_filter_ctx_t  *ctx;
+
+    ctx = ngx_http_get_module_ctx(r->main ? r->main : r,
+                                  ngx_http_write_filter_module);
+
+    if (ctx == NULL) {
+        ngx_http_create_ctx(r, ctx, ngx_http_write_filter_module,
+                            sizeof(ngx_http_write_filter_ctx_t), NGX_ERROR);
+    }
+
+    size = 0;
+    flush = 0;
+    last = 0;
+    ll = &ctx->out;
+
+    /* find the size, the flush point and the last link of the saved chain */
+
+    for (cl = ctx->out; cl; cl = cl->next) {
+        ll = &cl->next;
+
+        size += ngx_buf_size(cl->buf);
+
+        if (cl->buf->flush || cl->buf->recycled) {
+            flush = size;
+        }
+
+        if (cl->buf->last_buf) {
+            last = 1;
+        }
+    }
+
+    /* add the new chain to the existent one */
+
+    for (ln = in; ln; ln = ln->next) {
+        ngx_alloc_link_and_set_buf(cl, ln->buf, r->pool, NGX_ERROR);
+        *ll = cl;
+        ll = &cl->next;
+
+        size += ngx_buf_size(cl->buf);
+
+        if (cl->buf->flush || cl->buf->recycled) {
+            flush = size;
+        }
+
+        if (cl->buf->last_buf) {
+            last = 1;
+        }
+    }
+
+    c = r->connection;
+
+    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, c->log, 0,
+                   "http write filter: l:%d f:" OFF_T_FMT " s:" OFF_T_FMT,
+                   last, flush, size);
+
+    clcf = ngx_http_get_module_loc_conf(r->main ? r->main : r,
+                                        ngx_http_core_module);
+
+    /*
+     * avoid the output if there is no last buf, no flush point,
+     * there are the incoming bufs and the size of all bufs
+     * is smaller than "postpone_output" directive
+     */
+
+    if (!last && flush == 0 && in && size < (off_t) clcf->postpone_output) {
+        return NGX_OK;
+    }
+
+    if (c->write->delayed) {
+        return NGX_AGAIN;
+    }
+
+    if (size == 0 && !c->buffered) {
+        if (!last) {
+            ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
+                          "the http output chain is empty");
+        }
+        return NGX_OK;
+    }
+
+    sent = c->sent;
+
+    chain = c->send_chain(c, ctx->out,
+                          clcf->limit_rate ? clcf->limit_rate: OFF_T_MAX_VALUE);
+
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
+                   "http write filter %X", chain);
+
+    if (clcf->limit_rate) {
+        sent = c->sent - sent;
+        c->write->delayed = 1;
+        ngx_add_timer(r->connection->write,
+                      (ngx_msec_t) (sent * 1000 / clcf->limit_rate));
+    }
+
+    if (chain == NGX_CHAIN_ERROR) {
+        return NGX_ERROR;
+    }
+
+    ctx->out = chain;
+
+    if (chain || c->buffered) {
+        return NGX_AGAIN;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t ngx_http_write_filter_init(ngx_cycle_t *cycle)
+{
+    ngx_http_top_body_filter = ngx_http_write_filter;
+
+    return NGX_OK;
+}