new file mode 100644
--- /dev/null
+++ b/src/http/ngx_http_cache.c
@@ -0,0 +1,480 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+
+
+
+static ngx_http_module_t  ngx_http_cache_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_cache_module = {
+    NGX_MODULE,
+    &ngx_http_cache_module_ctx,            /* module context */
+    NULL,                                  /* module directives */
+    NGX_HTTP_MODULE,                       /* module type */
+    NULL,                                  /* init module */
+    NULL                                   /* init child */
+};
+
+
+ngx_http_cache_t *ngx_http_cache_get(ngx_http_cache_hash_t *hash,
+                                     ngx_http_cleanup_t *cleanup,
+                                     ngx_str_t *key, uint32_t *crc)
+{
+    ngx_uint_t         i;
+    ngx_http_cache_t  *c;
+
+    *crc = ngx_crc(key->data, key->len);
+
+    c = hash->elts + *crc % hash->hash * hash->nelts;
+
+    if (ngx_mutex_lock(&hash->mutex) == NGX_ERROR) {
+        return (void *) NGX_ERROR;
+    }
+
+    for (i = 0; i < hash->nelts; i++) {
+        if (c[i].crc == *crc
+            && c[i].key.len == key->len
+            && ngx_rstrncmp(c[i].key.data, key->data, key->len) == 0)
+        {
+#if 0
+            if (c[i].expired) {
+                ngx_mutex_unlock(&hash->mutex);
+                return (void *) NGX_AGAIN;
+            }
+#endif
+
+            c[i].refs++;
+
+            if ((!(c[i].notify && (ngx_event_flags & NGX_HAVE_KQUEUE_EVENT)))
+                && (ngx_cached_time - c[i].updated >= hash->update))
+            {
+                c[i].expired = 1;
+            }
+
+            ngx_mutex_unlock(&hash->mutex);
+
+            if (cleanup) {
+                cleanup->data.cache.hash = hash;
+                cleanup->data.cache.cache = &c[i];
+                cleanup->valid = 1;
+                cleanup->cache = 1;
+            }
+
+            return &c[i];
+        }
+    }
+
+    ngx_mutex_unlock(&hash->mutex);
+
+    return NULL;
+}
+
+
+ngx_http_cache_t *ngx_http_cache_alloc(ngx_http_cache_hash_t *hash,
+                                       ngx_http_cache_t *cache,
+                                       ngx_http_cleanup_t *cleanup,
+                                       ngx_str_t *key, uint32_t crc,
+                                       ngx_str_t *value, ngx_log_t *log)
+{
+    time_t             old;
+    ngx_uint_t         i;
+    ngx_http_cache_t  *c;
+
+    old = ngx_cached_time + 1;
+
+    c = hash->elts + crc % hash->hash * hash->nelts;
+
+    if (ngx_mutex_lock(&hash->mutex) == NGX_ERROR) {
+        return (void *) NGX_ERROR;
+    }
+
+    if (cache == NULL) {
+
+        /* allocate a new entry */
+
+        for (i = 0; i < hash->nelts; i++) {
+            if (c[i].refs > 0) {
+                /* a busy entry */
+                continue;
+            }
+
+            if (c[i].key.len == 0) {
+                /* a free entry is found */
+                cache = &c[i];
+                break;
+            }
+
+            /* looking for the oldest cache entry */
+
+            if (old > c[i].accessed) {
+
+                old = c[i].accessed;
+                cache = &c[i];
+            }
+        }
+
+        if (cache == NULL) {
+            ngx_mutex_unlock(&hash->mutex);
+            return NULL;
+        }
+
+        ngx_http_cache_free(cache, key, value, log);
+
+        if (cache->key.data == NULL) {
+            cache->key.data = ngx_alloc(key->len, log);
+            if (cache->key.data == NULL) {
+                ngx_http_cache_free(cache, NULL, NULL, log);
+                ngx_mutex_unlock(&hash->mutex);
+                return NULL;
+            }
+        }
+
+        cache->key.len = key->len;
+        ngx_memcpy(cache->key.data, key->data, key->len);
+
+    } else if (value) {
+        ngx_http_cache_free(cache, key, value, log);
+    }
+
+    if (value) {
+        if (cache->data.value.data == NULL) {
+            cache->data.value.data = ngx_alloc(value->len, log);
+            if (cache->data.value.data == NULL) {
+                ngx_http_cache_free(cache, NULL, NULL, log);
+                ngx_mutex_unlock(&hash->mutex);
+                return NULL;
+            }
+        }
+
+        cache->data.value.len = value->len;
+        ngx_memcpy(cache->data.value.data, value->data, value->len);
+    }
+
+    cache->crc = crc;
+    cache->key.len = key->len;
+
+    cache->refs = 1;
+    cache->count = 0;
+
+    cache->deleted = 0;
+    cache->expired = 0;
+    cache->memory = 0;
+    cache->mmap = 0;
+    cache->notify = 0;
+
+    if (cleanup) {
+        cleanup->data.cache.hash = hash;
+        cleanup->data.cache.cache = cache;
+        cleanup->valid = 1;
+        cleanup->cache = 1;
+    }
+
+    ngx_mutex_unlock(&hash->mutex);
+
+    return cache;
+}
+
+
+void ngx_http_cache_free(ngx_http_cache_t *cache,
+                         ngx_str_t *key, ngx_str_t *value, ngx_log_t *log)
+{
+    if (cache->memory) {
+        if (cache->data.value.data
+            && (value == NULL || value->len > cache->data.value.len))
+        {
+            ngx_free(cache->data.value.data);
+            cache->data.value.data = NULL;
+        }
+    }
+
+    /* TODO: mmap */
+
+    cache->data.value.len = 0;
+
+    if (cache->fd != NGX_INVALID_FILE) {
+
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0,
+                       "http cache close fd: %d", cache->fd);
+
+        if (ngx_close_file(cache->fd) == NGX_FILE_ERROR) {
+            ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
+                          ngx_close_file_n " \"%s\" failed",
+                          cache->key.data);
+        }
+
+        cache->fd = NGX_INVALID_FILE;
+    }
+
+    if (cache->key.data && (key == NULL || key->len > cache->key.len)) {
+        ngx_free(cache->key.data);
+        cache->key.data = NULL;
+    }
+
+    cache->key.len = 0;
+
+    cache->refs = 0;
+}
+
+
+void ngx_http_cache_lock(ngx_http_cache_hash_t *hash, ngx_http_cache_t *cache)
+{
+    if (ngx_mutex_lock(&hash->mutex) == NGX_ERROR) {
+        return;
+    }
+}
+
+
+void ngx_http_cache_unlock(ngx_http_cache_hash_t *hash,
+                           ngx_http_cache_t *cache, ngx_log_t *log)
+{
+    if (ngx_mutex_lock(&hash->mutex) == NGX_ERROR) {
+        return;
+    }
+
+    cache->refs--;
+
+    if (cache->refs == 0 && cache->deleted) {
+        ngx_http_cache_free(cache, NULL, NULL, log);
+    }
+
+    ngx_mutex_unlock(&hash->mutex);
+}
+
+
+#if 0
+
+ngx_http_cache_add_file_event(ngx_http_cache_hash_t *hash,
+                              ngx_http_cache_t *cache)
+{
+    ngx_event_t                 *ev;
+    ngx_http_cache_event_ctx_t  *ctx;
+
+    ev = &ngx_cycle->read_events[fd];
+    ngx_memzero(ev, sizeof(ngx_event_t);
+
+    ev->data = data;
+    ev->event_handler = ngx_http_cache_invalidate;
+
+    return ngx_add_event(ev, NGX_VNODE_EVENT, 0);
+}
+
+
+void ngx_http_cache_invalidate(ngx_event_t *ev)
+{
+    ngx_http_cache_event_ctx_t  *ctx;
+
+    ctx = ev->data;
+
+    ngx_http_cache_lock(&ctx->hash->mutex);
+
+    if (ctx->cache->refs == 0)
+        ngx_http_cache_free(ctx->cache, NULL, NULL, ctx->log);
+
+    } else {
+        ctx->cache->deleted = 1;
+    }
+
+    ngx_http_cache_unlock(&ctx->hash->mutex);
+}
+
+#endif
+
+
+/* TODO: currently fd only */
+
+ngx_int_t ngx_http_send_cached(ngx_http_request_t *r)
+{
+    ngx_int_t            rc;
+    ngx_hunk_t          *h;
+    ngx_chain_t          out;
+    ngx_http_log_ctx_t  *ctx;
+
+    ctx = r->connection->log->data;
+    ctx->action = "sending response to client";
+
+    r->headers_out.status = NGX_HTTP_OK;
+    r->headers_out.content_length_n = r->cache->data.size;
+    r->headers_out.last_modified_time = r->cache->last_modified;
+
+    if (ngx_http_set_content_type(r) != NGX_OK) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    /* we need to allocate all before the header would be sent */
+
+    if (!(h = ngx_pcalloc(r->pool, sizeof(ngx_hunk_t)))) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    if (!(h->file = ngx_pcalloc(r->pool, sizeof(ngx_file_t)))) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    rc = ngx_http_send_header(r);
+
+    if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
+        return rc;
+    }
+
+    h->type = r->main ? NGX_HUNK_FILE : NGX_HUNK_FILE|NGX_HUNK_LAST;
+
+    h->file_pos = 0;
+    h->file_last = r->cache->data.size;
+
+    h->file->fd = r->cache->fd;
+    h->file->log = r->connection->log;
+
+    out.hunk = h;
+    out.next = NULL;
+
+    return ngx_http_output_filter(r, &out);
+}
+
+
+char *ngx_http_set_cache_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    char  *p = conf;
+
+    ngx_int_t              i, j, dup, invalid;
+    ngx_str_t              *value, line;
+    ngx_http_cache_t       *c;
+    ngx_http_cache_hash_t  *ch, **chp;
+
+    chp = (ngx_http_cache_hash_t **) (p + cmd->offset);
+    if (*chp) {
+        return "is duplicate";
+    }
+
+    if (!(ch = ngx_pcalloc(cf->pool, sizeof(ngx_http_cache_hash_t)))) {
+        return NGX_CONF_ERROR;
+    }
+    *chp = ch;
+
+    dup = 0;
+    invalid = 0;
+
+    value = cf->args->elts;
+
+    for (i = 1; i < cf->args->nelts; i++) {
+
+        if (value[i].data[1] != '=') {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "invalid value \"%s\"", value[i].data);
+            return NGX_CONF_ERROR;
+        }
+
+        switch (value[i].data[0]) {
+
+        case 'h':
+            if (ch->hash) {
+                dup = 1;
+                break;
+            }
+
+            ch->hash = ngx_atoi(value[i].data + 2, value[i].len - 2);
+            if (ch->hash == (size_t)  NGX_ERROR || ch->hash == 0) {
+                invalid = 1;
+                break;
+            }
+
+            continue;
+
+        case 'n':
+            if (ch->nelts) {
+                dup = 1;
+                break;
+            }
+
+            ch->nelts = ngx_atoi(value[i].data + 2, value[i].len - 2);
+            if (ch->nelts == (size_t) NGX_ERROR || ch->nelts == 0) {
+                invalid = 1;
+                break;
+            }
+
+            continue;
+
+        case 'l':
+            if (ch->life) {
+                dup = 1;
+                break;
+            }
+
+            line.len = value[i].len - 2;
+            line.data = value[i].data + 2;
+
+            ch->life = ngx_parse_time(&line, 1);
+            if (ch->life == NGX_ERROR || ch->life == 0) {
+                invalid = 1;
+                break;
+            }
+
+            continue;
+
+        case 'u':
+            if (ch->update) {
+                dup = 1;
+                break;
+            }
+
+            line.len = value[i].len - 2;
+            line.data = value[i].data + 2;
+
+            ch->update = ngx_parse_time(&line, 1);
+            if (ch->update == NGX_ERROR || ch->update == 0) {
+                invalid = 1;
+                break;
+            }
+
+            continue;
+
+        default:
+            invalid = 1;
+        }
+
+        if (dup) {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "duplicate value \"%s\"", value[i].data);
+            return NGX_CONF_ERROR;
+        }
+
+        if (invalid) {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "invalid value \"%s\"", value[i].data);
+            return NGX_CONF_ERROR;
+        }
+    }
+
+    ch->elts = ngx_pcalloc(cf->pool,
+                           ch->hash * ch->nelts * sizeof(ngx_http_cache_t));
+    if (ch->elts == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    for (i = 0; i < (ngx_int_t) ch->hash; i++) {
+        c = ch->elts + i * ch->nelts;
+
+        for (j = 0; j < (ngx_int_t) ch->nelts; j++) {
+            c[j].fd = NGX_INVALID_FILE;
+        }
+    }
+
+    return NGX_CONF_OK;
+}