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Posted to dev@httpd.apache.org by Brian Akins <br...@turner.com> on 2006/01/20 19:19:37 UTC

[PATCH] mod_disk_cache: store/read array & table

This is a rather nasty patch (sorry).  Basically, it changes the way 
arrays and tables are stored on disk.  This allows us to do a much 
cleaner and quicker read_array and read_table.  It cuts down 
significantly on the number of disk reads for header files (one big one) 
and the number of strdup's (it used apr_table_addn, for example).

Bottom line is alot fewer system calls and allocations.  It gives me a 
5% increase in mod_disk_cache across the board.


-- 
Brian Akins
Lead Systems Engineer
CNN Internet Technologies

Re: [PATCH] mod_disk_cache: store/read array & table

Posted by Brian Akins <br...@turner.com>.
Ian Holsman wrote:

> does anyone have any objections to this patch?
> 5% is a pretty nice gain imho.
> 
> if I don't see anything in the next couple of days I'll commit it.

me for one!  I was just hoping to get some ideas flowing.  This is not 
meant to be for production.

-- 
Brian Akins
Lead Systems Engineer
CNN Internet Technologies

Re: [PATCH] mod_disk_cache: store/read array & table

Posted by Brian Akins <br...@turner.com>.
Ian Holsman wrote:

> 5% is a pretty nice gain imho.
>
Unfortunately, it still lags behind our mod_cache equivalent by at least 
20%.  There is something fundamentally slow about mod_cache that I 
cannot seem to put my finger on.  Granted, ours is highly customized and 
optimized, but I would expect stock mod_cache to within 10% of our 
custom module.  If I get time, I will try to massage our module into a 
mod_cache provider.  That would help me see if the bottleneck is in 
mod_disk_cache or mod_cache - or it may prove nothing.  I'm slammed this 
week, however.

I have no intentions of my patches being accepted as is (as are??), I 
just want to provoke some thought.  I'm still working from this side to 
allow us to release our code, but so far nothing :(

-- 
Brian Akins
Lead Systems Engineer
CNN Internet Technologies

Re: [PATCH] mod_disk_cache: store/read array & table

Posted by Ian Holsman <li...@holsman.net>.
Brian Akins wrote:
> This is a rather nasty patch (sorry).  Basically, it changes the way 
> arrays and tables are stored on disk.  This allows us to do a much 
> cleaner and quicker read_array and read_table.  It cuts down 
> significantly on the number of disk reads for header files (one big one) 
> and the number of strdup's (it used apr_table_addn, for example).
> 
> Bottom line is alot fewer system calls and allocations.  It gives me a 
> 5% increase in mod_disk_cache across the board.
> 

does anyone have any objections to this patch?
5% is a pretty nice gain imho.

if I don't see anything in the next couple of days I'll commit it.
> 
> 
> ------------------------------------------------------------------------
> 
> --- mod_disk_cache.c.orig	2006-01-18 13:44:55.000000000 -0500
> +++ mod_disk_cache.c	2006-01-20 09:48:23.000000000 -0500
> @@ -40,15 +40,15 @@
>   * Format #1:
>   *   apr_uint32_t format;
>   *   apr_time_t expire;
> - *   apr_array_t vary_headers (delimited by CRLF)
> + *   apr_array_t vary_headers (delimited by '\0')
>   *
>   * Format #2:
>   *   disk_cache_info_t (first sizeof(apr_uint32_t) bytes is the format)
>   *   entity name (dobj->name) [length is in disk_cache_info_t->name_len]
> - *   r->headers_out (delimited by CRLF)
> - *   CRLF
> - *   r->headers_in (delimited by CRLF)
> - *   CRLF
> + *   length of r->headers_out
> + *   r->headers_out (delimited by '\0')
> + *   length r->headers_in
> + *   r->headers_in (delimited by '\0')
>   */
>  
>  module AP_MODULE_DECLARE_DATA disk_cache_module;
> @@ -60,8 +60,12 @@
>  static apr_status_t recall_headers(cache_handle_t *h, request_rec *r);
>  static apr_status_t recall_body(cache_handle_t *h, apr_pool_t *p, apr_bucket_brigade *bb);
>  static apr_status_t read_array(request_rec *r, apr_array_header_t* arr,
> -                               apr_file_t *file);
> +                               meta_file_t *file);
>  
> +static apr_status_t meta_file_close(void *data);
> +static apr_status_t meta_file_open(meta_file_t **m, const char *file, apr_pool_t *pool);
> +static apr_status_t meta_file_read(meta_file_t *m, void **buf, apr_size_t *nbytes);
> +static apr_status_t meta_file_seek(meta_file_t *h, apr_off_t offset);
>  /*
>   * Local static functions
>   */
> @@ -195,46 +199,43 @@
>   * file for an ap_cache_el, this state information will be read
>   * and written transparent to clients of this module
>   */
> -static int file_cache_recall_mydata(apr_file_t *fd, cache_info *info,
> +static int file_cache_recall_mydata(meta_file_t *fd, cache_info *info,
>                                      disk_cache_object_t *dobj, request_rec *r)
>  {
>      apr_status_t rv;
>      char *urlbuff;
> -    disk_cache_info_t disk_info;
> +    disk_cache_info_t *disk_info;
>      apr_size_t len;
>  
>      /* read the data from the cache file */
>      len = sizeof(disk_cache_info_t);
> -    rv = apr_file_read_full(fd, &disk_info, len, &len);
> +    rv = meta_file_read(fd, (void **)&disk_info, &len);
>      if (rv != APR_SUCCESS) {
> +        /* Log error? */
>          return rv;
>      }
>  
>      /* Store it away so we can get it later. */
> -    dobj->disk_info = disk_info;
> +    dobj->disk_info = *disk_info;
>  
> -    info->status = disk_info.status;
> -    info->date = disk_info.date;
> -    info->expire = disk_info.expire;
> -    info->request_time = disk_info.request_time;
> -    info->response_time = disk_info.response_time;
> -
> -    /* Note that we could optimize this by conditionally doing the palloc
> -     * depending upon the size. */
> -    urlbuff = apr_palloc(r->pool, disk_info.name_len + 1);
> -    len = disk_info.name_len;
> -    rv = apr_file_read_full(fd, urlbuff, len, &len);
> -    if (rv != APR_SUCCESS) {
> -        return rv;
> -    }
> -    urlbuff[disk_info.name_len] = '\0';
> +    info->status = disk_info->status;
> +    info->date = disk_info->date;
> +    info->expire = disk_info->expire;
> +    info->request_time = disk_info->request_time;
> +    info->response_time = disk_info->response_time;
> +
> +    len = disk_info->name_len;
> +
> +    rv = meta_file_read(fd, (void **)&urlbuff, &len);
>  
>      /* check that we have the same URL */
> -    /* Would strncmp be correct? */
> -    if (strcmp(urlbuff, dobj->name) != 0) {
> +    if (strcmp(dobj->name, urlbuff)) {
> +          ap_log_error(APLOG_MARK, APLOG_INFO, 0, r->server,
> +                       "disk_cache: name mismatch: %s != %s",
> +                       urlbuff, dobj->name);
>          return APR_EGENERAL;
>      }
> -
> +    
>      return APR_SUCCESS;
>  }
>  
> @@ -347,7 +348,7 @@
>  
>  static int open_entity(cache_handle_t *h, request_rec *r, const char *key)
>  {
> -    apr_uint32_t format;
> +    apr_uint32_t format, *tf;
>      apr_size_t len;
>      const char *nkey;
>      apr_status_t rc;
> @@ -387,28 +388,32 @@
>  
>      dobj->hdrsfile = header_file(r->pool, conf, dobj, key);
>      flags = APR_READ|APR_BINARY|APR_BUFFERED;
> -    rc = apr_file_open(&dobj->hfd, dobj->hdrsfile, flags, 0, r->pool);
> +    rc = meta_file_open(&dobj->mf, dobj->hdrsfile, r->pool);
>      if (rc != APR_SUCCESS) {
> +        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
> +                     "disk_cache: meta_file_open");
>          return DECLINED;
>      }
>  
>      /* read the format from the cache file */
>      len = sizeof(format);
> -    apr_file_read_full(dobj->hfd, &format, len, &len);
> +    meta_file_read(dobj->mf, (void **)&tf, &len);
> +    format = *tf;
>  
>      if (format == VARY_FORMAT_VERSION) {
>          apr_array_header_t* varray;
> -        apr_time_t expire;
> +        apr_time_t expire, *te;
>  
>          len = sizeof(expire);
> -        apr_file_read_full(dobj->hfd, &expire, len, &len);
> +        meta_file_read(dobj->mf, (void **)&tf, &len);
> +        expire = *te;
>  
>          if (expire < r->request_time) {
>              return DECLINED;
>          }
>  
>          varray = apr_array_make(r->pool, 5, sizeof(char*));
> -        rc = read_array(r, varray, dobj->hfd);
> +        rc = read_array(r, varray, dobj->mf);
>          if (rc != APR_SUCCESS) {
>              ap_log_error(APLOG_MARK, APLOG_ERR, rc, r->server,
>                           "disk_cache: Cannot parse vary header file: %s",
> @@ -424,7 +429,7 @@
>          dobj->hdrsfile = header_file(r->pool, conf, dobj, nkey);
>  
>          flags = APR_READ|APR_BINARY|APR_BUFFERED;
> -        rc = apr_file_open(&dobj->hfd, dobj->hdrsfile, flags, 0, r->pool);
> +        rc = meta_file_open(&dobj->mf, dobj->hdrsfile, r->pool);
>          if (rc != APR_SUCCESS) {
>              return DECLINED;
>          }
> @@ -440,7 +445,7 @@
>          /* This wasn't a Vary Format file, so we must seek to the
>           * start of the file again, so that later reads work.
>           */
> -        apr_file_seek(dobj->hfd, APR_SET, &offset);
> +        meta_file_seek(dobj->mf, offset);
>          nkey = key;
>      }
>  
> @@ -457,6 +462,8 @@
>  #endif
>      rc = apr_file_open(&dobj->fd, dobj->datafile, flags, 0, r->pool);
>      if (rc != APR_SUCCESS) {
> +         ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
> +                      "disk_cache: apr_file_open");
>          /* XXX: Log message */
>          return DECLINED;
>      }
> @@ -467,8 +474,10 @@
>      }
>  
>      /* Read the bytes to setup the cache_info fields */
> -    rc = file_cache_recall_mydata(dobj->hfd, info, dobj, r);
> +    rc = file_cache_recall_mydata(dobj->mf, info, dobj, r);
>      if (rc != APR_SUCCESS) {
> +          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
> +                      "disk_cache: file_cache_recall_mydata");
>          /* XXX log message */
>          return DECLINED;
>      }
> @@ -572,152 +581,145 @@
>  
>      return OK;
>  }
> -
> -static apr_status_t read_array(request_rec *r, apr_array_header_t* arr,
> -                               apr_file_t *file)
> +static apr_status_t read_array(request_rec *r, apr_array_header_t* arr, 
> +                                      meta_file_t *m)
>  {
> -    char w[MAX_STRING_LEN];
> -    int p;
> -    apr_status_t rv;
>  
> -    while (1) {
> -        rv = apr_file_gets(w, MAX_STRING_LEN - 1, file);
> -        if (rv != APR_SUCCESS) {
> -            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
> -                          "Premature end of vary array.");
> -            return rv;
> -        }
> +    apr_size_t len, length;
> +    apr_size_t *tl;
> +    char *buffer;
> +    char *ptr, *end, *stop;
> +    apr_status_t rv;
> +    
> +    /*read length first*/
> +    len = sizeof(apr_size_t);
> +    
> +    if((rv = meta_file_read(m, (void **)&tl, &len)) != APR_SUCCESS) {
> +        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
> +                      "Premature end of vary array length.");
> +        return rv;
> +    }
> +    
> +    length = *tl;
>  
> -        p = strlen(w);
> -        if (p > 0 && w[p - 1] == '\n') {
> -            if (p > 1 && w[p - 2] == CR) {
> -                w[p - 2] = '\0';
> -            }
> -            else {
> -                w[p - 1] = '\0';
> -            }
> -        }
> +    len = length;
> +   
> +    if((rv = meta_file_read(m, (void **)&buffer, &len)) != APR_SUCCESS) {
> +        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
> +                      "Premature end of vary array data: %"APR_SIZE_T_FMT,
> +                      len);
> +        return rv;
> +    }
>  
> -        /* If we've finished reading the array, break out of the loop. */
> -        if (w[0] == '\0') {
> -            break;
> +    ptr = buffer;
> +    end = ptr + length;
> +    
> +    while (ptr < end) {
> +        if((stop = memchr(ptr, '\0', end - ptr)) != NULL) {
> +            *((const char **) apr_array_push(arr)) = ptr;
> +            ptr = stop + 1;
> +        } else {
> +            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
> +                          "Vary parse error.");
> +            return APR_EOF;
>          }
> -
> -       *((const char **) apr_array_push(arr)) = apr_pstrdup(r->pool, w);
>      }
> -
> + 
>      return APR_SUCCESS;
>  }
>  
> -static apr_status_t store_array(apr_file_t *fd, apr_array_header_t* arr)
> +static apr_status_t store_array(request_rec *r, apr_file_t *fd, apr_array_header_t* arr)
>  {
> -    int i;
> +    int i, j;
>      apr_status_t rv;
> -    struct iovec iov[2];
> -    apr_size_t amt;
> +    struct iovec *iov;
> +    apr_size_t amt = 0;
>      const char **elts;
> -
> +    apr_size_t length;
> +    
>      elts = (const char **) arr->elts;
> +    j = 1;
> +    length = 0;
>  
> +    iov = apr_pcalloc(r->pool, sizeof(struct iovec) * (arr->nelts + 1));
> +    
>      for (i = 0; i < arr->nelts; i++) {
> -        iov[0].iov_base = (char*) elts[i];
> -        iov[0].iov_len = strlen(elts[i]);
> -        iov[1].iov_base = CRLF;
> -        iov[1].iov_len = sizeof(CRLF) - 1;
> -
> -        rv = apr_file_writev(fd, (const struct iovec *) &iov, 2,
> -                             &amt);
> -        if (rv != APR_SUCCESS) {
> -            return rv;
> -        }
> +        
> +        iov[j].iov_base = (char*) elts[i];
> +        /*include '\0'*/
> +        iov[j].iov_len = strlen(elts[i]) + 1 ;
> +        
> +        length += iov[j].iov_len;
> +        j++;
>      }
>  
> -    iov[0].iov_base = CRLF;
> -    iov[0].iov_len = sizeof(CRLF) - 1;
>  
> -    return apr_file_writev(fd, (const struct iovec *) &iov, 1,
> +    
> +    iov[0].iov_base = &length;
> +    iov[0].iov_len = sizeof(apr_size_t);;
> +
> +    rv = apr_file_writev(fd, iov, j,
>                           &amt);
> +    
> +    return rv;
>  }
>  
> -static apr_status_t read_table(cache_handle_t *handle, request_rec *r,
> -                               apr_table_t *table, apr_file_t *file)
> +static apr_status_t read_table(request_rec *r, apr_table_t* t, 
> +                                      meta_file_t *m)
>  {
> -    char w[MAX_STRING_LEN];
> -    char *l;
> -    int p;
> +    char *buffer;
> +    char *ptr, *end;;
>      apr_status_t rv;
> -
> -    while (1) {
> -
> -        /* ### What about APR_EOF? */
> -        rv = apr_file_gets(w, MAX_STRING_LEN - 1, file);
> -        if (rv != APR_SUCCESS) {
> -            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
> -                          "Premature end of cache headers.");
> -            return rv;
> -        }
> -
> -        /* Delete terminal (CR?)LF */
> -
> -        p = strlen(w);
> -        /* Indeed, the host's '\n':
> -           '\012' for UNIX; '\015' for MacOS; '\025' for OS/390
> -           -- whatever the script generates.
> -        */
> -        if (p > 0 && w[p - 1] == '\n') {
> -            if (p > 1 && w[p - 2] == CR) {
> -                w[p - 2] = '\0';
> -            }
> -            else {
> -                w[p - 1] = '\0';
> -            }
> -        }
> -
> -        /* If we've finished reading the headers, break out of the loop. */
> -        if (w[0] == '\0') {
> -            break;
> -        }
> -
> -#if APR_CHARSET_EBCDIC
> -        /* Chances are that we received an ASCII header text instead of
> -         * the expected EBCDIC header lines. Try to auto-detect:
> -         */
> -        if (!(l = strchr(w, ':'))) {
> -            int maybeASCII = 0, maybeEBCDIC = 0;
> -            unsigned char *cp, native;
> -            apr_size_t inbytes_left, outbytes_left;
> -
> -            for (cp = w; *cp != '\0'; ++cp) {
> -                native = apr_xlate_conv_byte(ap_hdrs_from_ascii, *cp);
> -                if (apr_isprint(*cp) && !apr_isprint(native))
> -                    ++maybeEBCDIC;
> -                if (!apr_isprint(*cp) && apr_isprint(native))
> -                    ++maybeASCII;
> -            }
> -            if (maybeASCII > maybeEBCDIC) {
> -                ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
> -                             "CGI Interface Error: Script headers apparently ASCII: (CGI = %s)",
> -                             r->filename);
> -                inbytes_left = outbytes_left = cp - w;
> -                apr_xlate_conv_buffer(ap_hdrs_from_ascii,
> -                                      w, &inbytes_left, w, &outbytes_left);
> +    apr_size_t len, length, *tl;
> +    char *key, *val, *stop;
> +    int state;
> +#define KEY 0
> +#define VAL 1
> +    
> +    /*read length first*/
> +    len = sizeof(apr_size_t);
> +    
> +    if((rv = meta_file_read(m, (void **)&tl, &len)) != APR_SUCCESS) {
> +        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
> +                      "Premature end of table.");
> +        return rv;
> +    }
> +    
> +    length = (apr_size_t)*tl;
> +    
> +    len = length;
> +      
> +    if((rv = meta_file_read(m, (void **)&buffer, &len)) != APR_SUCCESS) {
> +        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
> +                      "Premature end of table data: %"APR_SIZE_T_FMT", %"APR_SIZE_T_FMT,
> +                      len, length);
> +        return rv;
> +    }
> +    
> +    ptr = buffer;
> +    end = ptr + len;
> +
> +    key = ptr;
> +    state = KEY;
> +    while (ptr < end) {
> +        if((stop = memchr(ptr, '\0', end - ptr)) != NULL) {
> +            
> +            if(state == VAL) {
> +                val = ptr;
> +                apr_table_addn(t, key, val);
> +                state = KEY;
> +            } else {
> +                key = ptr;
> +                state = VAL;
>              }
> +            ptr = stop + 1;
> +        } else {
> +            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
> +                          "Error parsing headers.");
> +            return APR_EOF;
>          }
> -#endif /*APR_CHARSET_EBCDIC*/
> -
> -        /* if we see a bogus header don't ignore it. Shout and scream */
> -        if (!(l = strchr(w, ':'))) {
> -            return APR_EGENERAL;
> -        }
> -
> -        *l++ = '\0';
> -        while (*l && apr_isspace(*l)) {
> -            ++l;
> -        }
> -
> -        apr_table_add(table, w, l);
>      }
> -
> +    
>      return APR_SUCCESS;
>  }
>  
> @@ -733,7 +735,7 @@
>      disk_cache_object_t *dobj = (disk_cache_object_t *) h->cache_obj->vobj;
>  
>      /* This case should not happen... */
> -    if (!dobj->hfd) {
> +    if (!dobj->mf) {
>          /* XXX log message */
>          return APR_NOTFOUND;
>      }
> @@ -742,10 +744,10 @@
>      h->resp_hdrs = apr_table_make(r->pool, 20);
>  
>      /* Call routine to read the header lines/status line */
> -    read_table(h, r, h->resp_hdrs, dobj->hfd);
> -    read_table(h, r, h->req_hdrs, dobj->hfd);
> +    read_table(r, h->resp_hdrs, dobj->mf);
> +    read_table(r, h->req_hdrs, dobj->mf);
>  
> -    apr_file_close(dobj->hfd);
> +    meta_file_close(dobj->mf);
>  
>      ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
>                   "disk_cache: Recalled headers for URL %s",  dobj->name);
> @@ -765,38 +767,44 @@
>  
>      return APR_SUCCESS;
>  }
> -
> -static apr_status_t store_table(apr_file_t *fd, apr_table_t *table)
> +static apr_status_t store_table(request_rec *r, apr_file_t *fd, apr_table_t* t)
>  {
> -    int i;
> +    int i, j;
>      apr_status_t rv;
> -    struct iovec iov[4];
> -    apr_size_t amt;
> +    struct iovec *iov;
> +    apr_size_t amt = 0;
> +    apr_size_t length;
>      apr_table_entry_t *elts;
> +     
> +    j = 1;
> +    length = 0;
> +    
> +    iov = apr_pcalloc(r->pool, sizeof(struct iovec) * (apr_table_elts(t)->nelts + 1) * 2);
> +    elts = (apr_table_entry_t *) apr_table_elts(t)->elts;
> +
> +     for (i = 0; i < apr_table_elts(t)->nelts; ++i) {
> +         if (elts[i].key != NULL) {
> +             iov[j].iov_base = (char*) elts[i].key;
> +             /*include /\0'*/
> +             iov[j].iov_len = strlen(elts[i].key) + 1;
> +             length += iov[j].iov_len;
> +             j++;
> +             
> +             iov[j].iov_base = (char*) elts[i].val;
> +             /*include /\0'*/
> +             iov[j].iov_len = strlen(elts[i].val) + 1;
> +             length += iov[j].iov_len;
> +             j++;
> +         }
> +             
> +    }
>  
> -    elts = (apr_table_entry_t *) apr_table_elts(table)->elts;
> -    for (i = 0; i < apr_table_elts(table)->nelts; ++i) {
> -        if (elts[i].key != NULL) {
> -            iov[0].iov_base = elts[i].key;
> -            iov[0].iov_len = strlen(elts[i].key);
> -            iov[1].iov_base = ": ";
> -            iov[1].iov_len = sizeof(": ") - 1;
> -            iov[2].iov_base = elts[i].val;
> -            iov[2].iov_len = strlen(elts[i].val);
> -            iov[3].iov_base = CRLF;
> -            iov[3].iov_len = sizeof(CRLF) - 1;
> +    iov[0].iov_base = &length;
> +    iov[0].iov_len = sizeof(apr_size_t);
>  
> -            rv = apr_file_writev(fd, (const struct iovec *) &iov, 4,
> -                                 &amt);
> -            if (rv != APR_SUCCESS) {
> -                return rv;
> -            }
> -        }
> -    }
> -    iov[0].iov_base = CRLF;
> -    iov[0].iov_len = sizeof(CRLF) - 1;
> -    rv = apr_file_writev(fd, (const struct iovec *) &iov, 1,
> +    rv = apr_file_writev(fd, iov, j,
>                           &amt);
> +    
>      return rv;
>  }
>  
> @@ -842,7 +850,7 @@
>              varray = apr_array_make(r->pool, 6, sizeof(char*));
>              tokens_to_array(r->pool, tmp, varray);
>  
> -            store_array(dobj->tfd, varray);
> +            store_array(r, dobj->tfd, varray);
>  
>              apr_file_close(dobj->tfd);
>  
> @@ -885,13 +893,19 @@
>      disk_info.response_time = info->response_time;
>      disk_info.status = info->status;
>  
> -    disk_info.name_len = strlen(dobj->name);
> +    disk_info.name_len = strlen(dobj->name) + 1;
>  
>      iov[0].iov_base = (void*)&disk_info;
>      iov[0].iov_len = sizeof(disk_cache_info_t);
>      iov[1].iov_base = (void*)dobj->name;
>      iov[1].iov_len = disk_info.name_len;
>  
> +    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
> +                 "disk_cache: store_headers: name = %s, len = %d, %"APR_TIME_T_FMT,
> +                 dobj->name, disk_info.name_len, disk_info.request_time
> +                 );
> +    
> +    
>      rv = apr_file_writev(dobj->hfd, (const struct iovec *) &iov, 2, &amt);
>      if (rv != APR_SUCCESS) {
>          return rv;
> @@ -911,7 +925,7 @@
>  
>          headers_out = apr_table_overlay(r->pool, headers_out,
>                                          r->err_headers_out);
> -        rv = store_table(dobj->hfd, headers_out);
> +        rv = store_table(r, dobj->hfd, headers_out);
>          if (rv != APR_SUCCESS) {
>              return rv;
>          }
> @@ -924,7 +938,7 @@
>  
>          headers_in = ap_cache_cacheable_hdrs_out(r->pool, r->headers_in,
>                                                   r->server);
> -        rv = store_table(dobj->hfd, headers_in);
> +        rv = store_table(r, dobj->hfd, headers_in);
>          if (rv != APR_SUCCESS) {
>              return rv;
>          }
> @@ -1164,3 +1178,86 @@
>      disk_cache_cmds,            /* command apr_table_t */
>      disk_cache_register_hook    /* register hooks */
>  };
> +
> +static apr_status_t meta_file_close(void *data) {
> +    return APR_SUCCESS;
> +}  
> +
> +static apr_status_t meta_file_open(meta_file_t **m, const char *file, apr_pool_t *pool) {
> +    apr_finfo_t finfo;
> +    apr_status_t rv;
> +    apr_size_t len;
> +    meta_file_t *new = NULL;
> +    apr_file_t *fd;
> +    
> +    if((rv = apr_file_open(&fd, file, APR_READ|APR_BINARY, 0, pool)) != APR_SUCCESS) {
> +        return rv;
> +    }
> +    
> +    if((rv = apr_file_info_get(&finfo, APR_FINFO_SIZE, fd)) != APR_SUCCESS) {
> +        return rv;
> +    }
> +
> +    new = apr_pcalloc(pool, sizeof(meta_file_t));
> +    
> +    new->pool = pool;
> +    new->name = (char *)file;
> +    new->bufflen = finfo.size;
> +
> +    new->buffer = apr_pcalloc(new->pool, new->bufflen);
> +    
> +    len = new->bufflen;
> +    
> +    if((rv = apr_file_read_full(fd, new->buffer, len, &len)) != APR_SUCCESS) {
> +        return rv;
> +    }
> +    
> +    apr_file_close(fd);
> +    
> +    new->curr = new->buffer;
> +
> +    apr_pool_cleanup_register(new->pool, (void *)new,
> +                              meta_file_close,
> +                              meta_file_close);
> +
> +
> +    *m = new;
> +
> +    return APR_SUCCESS;
> +}                                                           
> +
> +static apr_status_t meta_file_read(meta_file_t *m, void **buf, apr_size_t *nbytes) {
> +    apr_size_t len;
> +
> +    if(*nbytes < 0) {
> +        return APR_EGENERAL;
> +    }
> +    
> +    len = (m->buffer + m->bufflen) - m->curr;
> +
> +    /*quick check are we EOF?*/
> +    if(len <= 0) {
> +        return APR_EOF;
> +    }
> +    
> +    *buf = m->curr;
> +
> +    if(*nbytes > len) {
> +        m->curr += len;
> +        *nbytes = len;
> +        return APR_EOF;
> +    }
> +
> +    m->curr += *nbytes;
> +        
> +    return APR_SUCCESS;
> +}
> +
> +static apr_status_t meta_file_seek(meta_file_t *m, apr_off_t offset) {
> +    if(offset > m->bufflen) {
> +        return APR_EOF;
> +    } else {
> +        m->curr = m->buffer + offset; 
> +    }
> +    return APR_SUCCESS;
> +} 
> --- mod_disk_cache.h.orig	2006-01-18 13:48:13.000000000 -0500
> +++ mod_disk_cache.h	2006-01-20 09:44:53.000000000 -0500
> @@ -22,7 +22,7 @@
>   */
>  
>  #define VARY_FORMAT_VERSION 3
> -#define DISK_FORMAT_VERSION 4
> +#define DISK_FORMAT_VERSION 5
>  
>  #define CACHE_HEADER_SUFFIX ".header"
>  #define CACHE_DATA_SUFFIX   ".data"
> @@ -36,6 +36,15 @@
>  #define AP_TEMPFILE AP_TEMPFILE_PREFIX AP_TEMPFILE_BASE AP_TEMPFILE_SUFFIX
>  
>  typedef struct {
> +    apr_pool_t *pool;
> +    apr_file_t *fd;
> +    char *name; /*name of file we opened*/
> +    char *buffer; /*buffer that holds disk_info*/
> +    char *curr;  /*current pointer in buffer*/
> +    apr_size_t bufflen;
> +} meta_file_t;
> +                                                                                                      
> +typedef struct {
>      /* Indicates the format of the header struct stored on-disk. */
>      apr_uint32_t format;
>      /* The HTTP status code returned for this response.  */
> @@ -68,6 +77,7 @@
>      apr_file_t *fd;          /* data file */
>      apr_file_t *hfd;         /* headers file */
>      apr_file_t *tfd;         /* temporary file for data */
> +    meta_file_t *mf;
>      apr_off_t file_size;     /*  File size of the cached data file  */
>      disk_cache_info_t disk_info; /* Header information. */
>  } disk_cache_object_t;