[qpid-proton] 01/16: PROTON-2447: Added API to pn_buffer to get access to available memory

[as...@apache.org]

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astitcher pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/qpid-proton.git

commit 42a1ae5783ace2ad8f35cb9f8259486735185356
Author: Andrew Stitcher <as...@apache.org>
AuthorDate: Wed May 12 14:04:50 2021 -0400

    PROTON-2447: Added API to pn_buffer to get access to available memory
---
 c/src/core/buffer.c | 37 +++++++++++++++++++++++++------------
 c/src/core/buffer.h |  1 +
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/c/src/core/buffer.c b/c/src/core/buffer.c
index 8e7d73d..5b697d6 100644
--- a/c/src/core/buffer.c
+++ b/c/src/core/buffer.c
@@ -293,24 +293,37 @@ int pn_buffer_defrag(pn_buffer_t *buf)
 
 pn_bytes_t pn_buffer_bytes(pn_buffer_t *buf)
 {
-  if (buf) {
-    pn_buffer_defrag(buf);
-    return pn_bytes(buf->size, buf->bytes);
-  } else {
-    return pn_bytes(0, NULL);
+  if (!buf) {
+    return (pn_bytes_t){0, NULL};
   }
+  pn_buffer_defrag(buf);
+  return (pn_bytes_t){.size=buf->size, .start=buf->bytes};
 }
 
 pn_rwbytes_t pn_buffer_memory(pn_buffer_t *buf)
 {
-  if (buf) {
-    pn_buffer_defrag(buf);
-    pn_rwbytes_t r = {buf->size, buf->bytes};
-    return r;
-  } else {
-    pn_rwbytes_t r = {0, NULL};
-    return r;
+  if (!buf) {
+    return (pn_rwbytes_t){0, NULL};
+  }
+  pn_buffer_defrag(buf);
+  return (pn_rwbytes_t){.size=buf->size, .start=buf->bytes};
+}
+
+pn_rwbytes_t pn_buffer_free_memory(pn_buffer_t *buf)
+{
+  if (!buf) {
+    return (pn_rwbytes_t){0, NULL};
+  }
+  size_t free_size = buf->capacity-buf->size;
+  if (buf->start == 0) {
+    return (pn_rwbytes_t){.size=free_size, .start=buf->bytes};
+  }
+  // If free memory in one single blob don't need to defragment
+  if (buf->start+buf->size > buf->capacity) {
+    return (pn_rwbytes_t){.size=free_size, .start=buf->bytes+buf->start-free_size};
   }
+  pn_buffer_defrag(buf);
+  return (pn_rwbytes_t){.size=free_size, .start=buf->bytes+buf->start+buf->size};
 }
 
 int pn_buffer_quote(pn_buffer_t *buf, pn_string_t *str, size_t n)
diff --git a/c/src/core/buffer.h b/c/src/core/buffer.h
index 7193f8f..b9bd757 100644
--- a/c/src/core/buffer.h
+++ b/c/src/core/buffer.h
@@ -46,6 +46,7 @@ void pn_buffer_clear(pn_buffer_t *buf);
 int pn_buffer_defrag(pn_buffer_t *buf);
 pn_bytes_t pn_buffer_bytes(pn_buffer_t *buf);
 pn_rwbytes_t pn_buffer_memory(pn_buffer_t *buf);
+pn_rwbytes_t pn_buffer_free_memory(pn_buffer_t *buf);
 int pn_buffer_quote(pn_buffer_t *buf, pn_string_t *string, size_t n);
 
 #ifdef __cplusplus

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