Support fetching the memory usage of a delta index

Delta indices, at least on 64-bit platforms, tend to be larger than
the actual uncompressed data.  As such, keeping track of this storage
is important if you want to successfully limit the memory size of your
pack window.

Squirrel away the total allocation size inside the delta_index struct,
and add an accessor "sizeof_delta_index" to access it.

Signed-off-by: Brian Downing <bdowning@lavos.net>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/delta.h b/delta.h
index 7b3f86d85f71e47d11c40a4abbcd9d9f499a6636..40ccf5a1e95f62d840a006274f7024fa43208b1c 100644 (file)
--- a/delta.h
+++ b/delta.h
@@ -23,6 +23,13 @@ create_delta_index(const void *buf, unsigned long bufsize);
  */
 extern void free_delta_index(struct delta_index *index);
 
+/*
+ * sizeof_delta_index: returns memory usage of delta index
+ *
+ * Given pointer must be what create_delta_index() returned, or NULL.
+ */
+extern unsigned long sizeof_delta_index(struct delta_index *index);
+
 /*
  * create_delta: create a delta from given index for the given buffer
  *

diff --git a/diff-delta.c b/diff-delta.c
index faf96e47130e3a2af26f55fc1173874f078617fc..3af583536f2ee9f2d1f2fd699148ff16166dc932 100644 (file)
--- a/diff-delta.c
+++ b/diff-delta.c
@@ -119,6 +119,7 @@ struct index_entry {
 };
 
 struct delta_index {
+       unsigned long memsize;
        const void *src_buf;
        unsigned long src_size;
        unsigned int hash_mask;
@@ -159,6 +160,7 @@ struct delta_index * create_delta_index(const void *buf, unsigned long bufsize)
        mem = hash + hsize;
        entry = mem;
 
+       index->memsize = memsize;
        index->src_buf = buf;
        index->src_size = bufsize;
        index->hash_mask = hmask;
@@ -228,6 +230,14 @@ void free_delta_index(struct delta_index *index)
        free(index);
 }
 
+unsigned long sizeof_delta_index(struct delta_index *index)
+{
+       if (index)
+               return index->memsize;
+       else
+               return 0;
+}
+
 /*
  * The maximum size for any opcode sequence, including the initial header
  * plus Rabin window plus biggest copy.