Add MAX_DELTA_CMD in job.h for buffer scaling.

This gives us a single point for defining the size used for delta commands and
streaming buffers.

In job.h define MAX_DELTA_CMD to be the maximum size of a single delta command
at 64K.

In delta.c use MAX_DELTA_CMD to define MAX_MISS_LEN and use it to get the
minimum readahead size in rs_getinput().

In whole.c use MAX_DELTA_CMD for defining the buffer sizes used for delta and
patch operations.

3 files changed, 15 insertions, 9 deletions

diff --git a/src/delta.c b/src/delta.c
index fcfcf5a..9ee56e7 100644
--- a/src/delta.c
+++ b/src/delta.c
@@ -99,7 +99,7 @@
 #include "trace.h"
 
 /** Max length of a miss is 64K including 3 command bytes. */
-#define MAX_MISS_LEN ((1<<16)-3)
+#define MAX_MISS_LEN (MAX_DELTA_CMD - 3)
 
 static rs_result rs_delta_s_scan(rs_job_t *job);
 static rs_result rs_delta_s_flush(rs_job_t *job);
@@ -208,7 +208,7 @@ static rs_result rs_delta_s_end(rs_job_t *job)
 
 static inline rs_result rs_getinput(rs_job_t *job, size_t block_len)
 {
-    size_t min_len = block_len + MAX_MISS_LEN + 1;
+    size_t min_len = block_len + MAX_DELTA_CMD;
 
     job->scan_len = rs_scoop_avail(job);
     if (job->scan_len < min_len && !job->stream->eof_in)
diff --git a/src/job.h b/src/job.h
index b9d9ae7..fb22461 100644
--- a/src/job.h
+++ b/src/job.h
@@ -35,6 +35,14 @@
 #  include "checksum.h"
 #  include "librsync.h"
 
+/** Magic job tag number for checking jobs have been initialized. */
+#  define RS_JOB_TAG 20010225
+
+/** Max length of a singled delta command is including command bytes.
+ *
+ * This is used to constrain and set the internal buffer sizes. */
+#  define MAX_DELTA_CMD (1<<16)
+
 /** The contents of this structure are private. */
 struct rs_job {
     int dogtag;
@@ -115,9 +123,6 @@ struct rs_job {
 
 rs_job_t *rs_job_new(const char *, rs_result (*statefn)(rs_job_t *));
 
-/** Magic job tag number for checking jobs have been initialized. */
-#  define RS_JOB_TAG 20010225
-
 /** Assert that a job is valid.
  *
  * We don't use a static inline function here so that assert failure output
diff --git a/src/whole.c b/src/whole.c
index ec44967..e667f88 100644
--- a/src/whole.c
+++ b/src/whole.c
@@ -111,9 +111,9 @@ rs_result rs_delta_file(rs_signature_t *sig, FILE *new_file, FILE *delta_file,
     rs_result r;
 
     job = rs_delta_begin(sig);
-    /* Size inbuf for 4*(64K + 1 block), outbuf for 4*(64K). */
+    /* Size inbuf for 4*(CMD + 1 block), outbuf for 4*CMD. */
     r = rs_whole_run(job, new_file, delta_file,
-                     4 * ((1 << 16) + sig->block_len), 4 * (1 << 16));
+                     4 * (MAX_DELTA_CMD + sig->block_len), 4 * MAX_DELTA_CMD);
     if (stats)
         memcpy(stats, &job->stats, sizeof *stats);
     rs_job_free(job);
@@ -127,8 +127,9 @@ rs_result rs_patch_file(FILE *basis_file, FILE *delta_file, FILE *new_file,
     rs_result r;
 
     job = rs_patch_begin(rs_file_copy_cb, basis_file);
-    /* Default size inbuf and outbuf 64K. */
-    r = rs_whole_run(job, delta_file, new_file, 64 * 1024, 64 * 1024);
+    /* Default size inbuf 1*CMD and outbuf 4*CMD. */
+    r = rs_whole_run(job, delta_file, new_file, MAX_DELTA_CMD,
+                     4 * MAX_DELTA_CMD);
     if (stats)
         memcpy(stats, &job->stats, sizeof *stats);
     rs_job_free(job);