Fixed entry size calculation for the max-size cache_dir selection algorithms.

There were two sides of this bug.

In src/store_swapout.cc, we must create metadata earlier because storeCreate()
needs swap_hdr_sz. With swap_hdr_sz unknown at the time of storeCreate(), the
SwapDir selection algorithms may select SwapDirs that should not really take
the entry as the real storage size (with the metadata swap_hdr_sz) would
exceed the store slot size.

In src/store_dir.cc, we must add the metadata size before looking for
cache_dirs that accept objsize. Only the "new" storeDirSelectSwapDirRoundRobin
selection scheme was affected.

=== modified file 'src/store_dir.cc'
--- src/store_dir.cc	2009-05-30 13:38:39 +0000
+++ src/store_dir.cc	2009-09-02 04:59:32 +0000
@@ -189,6 +189,10 @@
     int load;
     RefCount<SwapDir> sd;
 
+    ssize_t objsize = e->objectLen();
+    if (objsize != -1)
+        objsize += e->mem_obj->swap_hdr_sz;
+
     for (i = 0; i <= Config.cacheSwap.n_configured; i++) {
         if (++dirn >= Config.cacheSwap.n_configured)
             dirn = 0;
@@ -201,7 +205,7 @@
         if (sd->cur_size > sd->max_size)
             continue;
 
-        if (!sd->objectSizeIsAcceptable(e->objectLen()))
+        if (!sd->objectSizeIsAcceptable(objsize))
             continue;
 
         /* check for error or overload condition */

=== modified file 'src/store_swapout.cc'
--- src/store_swapout.cc	2009-02-01 10:09:23 +0000
+++ src/store_swapout.cc	2009-09-02 05:23:45 +0000
@@ -63,6 +63,15 @@
     /* If we start swapping out objects with OutOfBand Metadata,
      * then this code needs changing
      */
+
+    /* TODO: make some sort of data,size refcounted immutable buffer
+     * and stop fooling ourselves with "const char*" buffers.
+     */
+
+    // Create metadata now, possibly in vain: storeCreate needs swap_hdr_sz.
+    const char *buf = e->getSerialisedMetaData ();
+    assert(buf);
+
     /* Create the swap file */
     generic_cbdata *c = new generic_cbdata(e);
     sio = storeCreate(e, storeSwapOutFileNotify, storeSwapOutFileClosed, c);
@@ -70,6 +79,7 @@
     if (sio == NULL) {
         e->swap_status = SWAPOUT_NONE;
         delete c;
+        xfree((char*)buf);
         storeLog(STORE_LOG_SWAPOUTFAIL, e);
         return;
     }
@@ -85,16 +95,6 @@
     e->swap_dirn = mem->swapout.sio->swap_dirn;
 
     /* write out the swap metadata */
-    /* TODO: make some sort of data,size refcounted immutable buffer
-     * for use by this sort of function.
-     */
-    char const *buf = e->getSerialisedMetaData ();
-
-    /* If we start swapping out with out of band metadata, this assert
-     * will catch it - this code needs to be adjusted if that happens
-     */
-    assert (buf);
-
     storeIOWrite(mem->swapout.sio, buf, mem->swap_hdr_sz, 0, xfree);
 }