CURLOPT_UPLOAD_BUFFERSIZE: set upload buffer size

This is step 3 of #2888.

Fixes #2888
Closes #2896

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/url.h b/lib/url.h
index a914f56e6..618309d38 100644
--- a/lib/url.h
+++ b/lib/url.h
@@ -27,6 +27,18 @@
 #define READBUFFER_MAX  CURL_MAX_READ_SIZE
 #define READBUFFER_MIN  1024
 
+/* The default upload buffer size, should not be smaller than
+   CURL_MAX_WRITE_SIZE, as it needs to hold a full buffer as could be sent in
+   a write callback.
+
+   The size was 16KB for many years but was bumped to 64KB because it makes
+   libcurl able to do significantly faster uploads in some circumstances. Even
+   larger buffers can help further, but this is deemed a fair memory/speed
+   compromise. */
+#define UPLOADBUFFER_DEFAULT 65536
+#define UPLOADBUFFER_MAX (2*1024*1024)
+#define UPLOADBUFFER_MIN CURL_MAX_WRITE_SIZE
+
 /*
  * Prototypes for library-wide functions provided by url.c
  */