Reduce unnecessary copying during chunk compression

[wimlib] / include / wimlib / chunk_compressor.h

diff --git a/include/wimlib/chunk_compressor.h b/include/wimlib/chunk_compressor.h
index f21a0c6a7bd9fcf5d7e755a94223291cd4db3557..265e1362438a39c9238fe9d67657d65cf2d59f27 100644 (file)
--- a/include/wimlib/chunk_compressor.h
+++ b/include/wimlib/chunk_compressor.h
@@ -23,16 +23,20 @@ struct chunk_compressor {
        /* Free the chunk compressor.  */
        void (*destroy)(struct chunk_compressor *);
 
-       /* Submit a chunk of uncompressed data for compression.
+       /* Try to borrow a buffer into which the uncompressed data for the next
+        * chunk should be prepared.
         *
-        * The chunk must have size greater than 0 and less than or equal to
-        * @out_chunk_size.
+        * Only one buffer can be borrowed at a time.
         *
-        * The return value is %true if the chunk was successfully submitted, or
-        * %false if the chunk compressor does not have space for the chunk at
-        * the present time.  In the latter case, get_chunk() must be called to
-        * retrieve a compressed chunk before trying again.  */
-       bool (*submit_chunk)(struct chunk_compressor *, const void *, u32);
+        * Returns a pointer to the buffer, or NULL if no buffer is available.
+        * If no buffer is available, you must call ->get_compression_result()
+        * to retrieve a compressed chunk before trying again.  */
+       void *(*get_chunk_buffer)(struct chunk_compressor *);
+
+       /* Signals to the chunk compressor that the buffer which was loaned out
+        * from ->get_chunk_buffer() has finished being filled and contains the
+        * specified number of bytes of uncompressed data.  */
+       void (*signal_chunk_filled)(struct chunk_compressor *, u32);
 
        /* Get the next chunk of compressed data.
         *
@@ -52,8 +56,8 @@ struct chunk_compressor {
         * The return value is %true if a chunk of compressed data was
         * successfully retrieved, or %false if there are no chunks currently
         * being compressed.  */
-       bool (*get_chunk)(struct chunk_compressor *,
-                         const void **, u32 *, u32 *);
+       bool (*get_compression_result)(struct chunk_compressor *,
+                                      const void **, u32 *, u32 *);
 };