nghttp2_bufs: Add chunk_keep to specify the number of buffers to keep on reset

lib/nghttp2_buf.c

@@ -131,11 +131,17 @@ int nghttp2_bufs_init(nghttp2_bufs *bufs, size_t chunk_length,
 
 int nghttp2_bufs_init2(nghttp2_bufs *bufs, size_t chunk_length,
                        size_t max_chunk, size_t offset)
+{
+  return nghttp2_bufs_init3(bufs, chunk_length, max_chunk, max_chunk, offset);
+}
+
+int nghttp2_bufs_init3(nghttp2_bufs *bufs, size_t chunk_length,
+                       size_t max_chunk, size_t chunk_keep, size_t offset)
 {
   int rv;
   nghttp2_buf_chain *chain;
 
-  if(max_chunk == 0 || chunk_length < offset) {
+  if(chunk_keep == 0 || max_chunk < chunk_keep || chunk_length < offset) {
     return NGHTTP2_ERR_INVALID_ARGUMENT;
   }
 
@@ -152,7 +158,9 @@ int nghttp2_bufs_init2(nghttp2_bufs *bufs, size_t chunk_length,
   nghttp2_buf_shift_right(&bufs->cur->buf, offset);
 
   bufs->chunk_length = chunk_length;
-  bufs->chunk_left = max_chunk - 1;
+  bufs->chunk_used = 1;
+  bufs->max_chunk = max_chunk;
+  bufs->chunk_keep = chunk_keep;
 
   return 0;
 }
@@ -199,7 +207,7 @@ ssize_t nghttp2_bufs_len(nghttp2_bufs *bufs)
 static int nghttp2_bufs_avail(nghttp2_bufs *bufs)
 {
   return nghttp2_buf_avail(&bufs->cur->buf) +
-    (bufs->chunk_length - bufs->offset) * bufs->chunk_left;
+    (bufs->chunk_length - bufs->offset) * (bufs->max_chunk - bufs->chunk_used);
 }
 
 static int nghttp2_bufs_alloc_chain(nghttp2_bufs *bufs)
@@ -213,7 +221,7 @@ static int nghttp2_bufs_alloc_chain(nghttp2_bufs *bufs)
     return 0;
   }
 
-  if(bufs->chunk_left == 0) {
+  if(bufs->max_chunk == bufs->chunk_used) {
     return NGHTTP2_ERR_BUFFER_ERROR;
   }
 
@@ -226,7 +234,7 @@ static int nghttp2_bufs_alloc_chain(nghttp2_bufs *bufs)
                  "new buffer %zu bytes allocated for bufs %p, left %zu\n",
                  bufs->chunk_length, bufs, bufs->chunk_left));
 
-  --bufs->chunk_left;
+  ++bufs->chunk_used;
 
   bufs->cur->next = chain;
   bufs->cur = chain;
@@ -382,11 +390,33 @@ ssize_t nghttp2_bufs_remove(nghttp2_bufs *bufs, uint8_t **out)
 
 void nghttp2_bufs_reset(nghttp2_bufs *bufs)
 {
-  nghttp2_buf_chain *chain;
+  nghttp2_buf_chain *chain, *ci;
+  size_t k;
 
-  for(chain = bufs->head; chain; chain = chain->next) {
-    nghttp2_buf_reset(&chain->buf);
-    nghttp2_buf_shift_right(&chain->buf, bufs->offset);
+  k = bufs->chunk_keep;
+
+  for(ci = bufs->head; ci; ci = ci->next) {
+    nghttp2_buf_reset(&ci->buf);
+    nghttp2_buf_shift_right(&ci->buf, bufs->offset);
+
+    if(--k == 0) {
+      break;
+    }
+  }
+
+  if(ci) {
+    chain = ci->next;
+    ci->next = NULL;
+
+    for(ci = chain; ci;) {
+      chain = ci->next;
+
+      nghttp2_buf_chain_del(ci);
+
+      ci = chain;
+    }
+
+    bufs->chunk_used = bufs->chunk_keep;
   }
 
   bufs->cur = bufs->head;

lib/nghttp2_buf.h

@@ -154,7 +154,11 @@ typedef struct {
   /* The buffer capacity of each buf */
   size_t chunk_length;
   /* The maximum number of nghttp2_buf_chain */
-  size_t chunk_left;
+  size_t max_chunk;
+  /* The number of nghttp2_buf_chain allocated */
+  size_t chunk_used;
+  /* The number of nghttp2_buf_chain to keep on reset */
+  size_t chunk_keep;
   /* pos offset from begin in each buffers. On initialization and
      reset, buf->pos and buf->last are positioned at buf->begin +
      offset. */
@@ -168,11 +172,19 @@ typedef struct {
 int nghttp2_bufs_init(nghttp2_bufs *bufs, size_t chunk_length,
                       size_t max_chunk);
 
+/*
+ * This is the same as calling nghttp2_bufs_init3 with the given
+ * arguments and chunk_keep = max_chunk.
+ */
+int nghttp2_bufs_init2(nghttp2_bufs *bufs, size_t chunk_length,
+                       size_t max_chunk, size_t offset);
+
 /*
  * Initializes |bufs|. Each buffer size is given in the
  * |chunk_length|.  The maximum number of buffers is given in the
- * |max_chunk|. Each buffer will have bufs->pos and bufs->last shifted
- * to left by |offset| bytes on creation and reset.
+ * |max_chunk|.  On reset, first |chunk_keep| buffers are kept and
+ * remaining buffers are deleted.  Each buffer will have bufs->pos and
+ * bufs->last shifted to left by |offset| bytes on creation and reset.
  *
  * This function allocates first buffer.  bufs->head and bufs->cur
  * will point to the first buffer after this call.
@@ -183,10 +195,11 @@ int nghttp2_bufs_init(nghttp2_bufs *bufs, size_t chunk_length,
  * NGHTTP2_ERR_NOMEM
  *     Out of memory.
  * NGHTTP2_ERR_INVALID_ARGUMENT
- *     max_chunk is 0
+ *     chunk_keep is 0; or max_chunk < chunk_keep; or offset is too
+ *     long.
  */
-int nghttp2_bufs_init2(nghttp2_bufs *bufs, size_t chunk_length,
-                       size_t max_chunk, size_t offset);
+int nghttp2_bufs_init3(nghttp2_bufs *bufs, size_t chunk_length,
+                       size_t max_chunk, size_t chunk_keep, size_t offset);
 
 /*
  * Frees any related resources to the |bufs|.

lib/nghttp2_session.c

@@ -291,9 +291,10 @@ static int nghttp2_session_new(nghttp2_session **session_ptr,
 
   /* 2 for PAD_HIGH and PAD_LOW. We have maximum 64KB of frame
      serialization buffer for transmission */
-  rv = nghttp2_bufs_init2(&(*session_ptr)->aob.framebufs,
+  rv = nghttp2_bufs_init3(&(*session_ptr)->aob.framebufs,
                           NGHTTP2_MAX_FRAMELEN,
-                          65536 / NGHTTP2_MAX_FRAMELEN,
+                          (1 << 17) / NGHTTP2_MAX_FRAMELEN,
+                          (1 << 13) / NGHTTP2_MAX_FRAMELEN,
                           NGHTTP2_FRAME_HDLEN + 2);
   if(rv != 0) {
     goto fail_aob_framebuf;

tests/nghttp2_buf_test.c

@@ -203,7 +203,7 @@ void test_nghttp2_bufs_reset(void)
   nghttp2_buf_chain *ci;
   ssize_t offset = 9;
 
-  rv = nghttp2_bufs_init2(&bufs, 250, 3, offset);
+  rv = nghttp2_bufs_init3(&bufs, 250, 3, 1, offset);
   CU_ASSERT(0 == rv);
 
   rv = nghttp2_bufs_add(&bufs, "foo", 3);
@@ -227,6 +227,8 @@ void test_nghttp2_bufs_reset(void)
     CU_ASSERT(ci->buf.pos == ci->buf.last);
   }
 
+  CU_ASSERT(bufs.head->next == NULL);
+
   nghttp2_bufs_free(&bufs);
 }
 

tests/nghttp2_session_test.c

@@ -1996,7 +1996,7 @@ void test_nghttp2_session_send_headers_header_comp_error(void)
   nghttp2_nv *nva;
   ssize_t nvlen;
   size_t vallen = NGHTTP2_HD_MAX_VALUE;
-  nghttp2_nv nv[16];
+  nghttp2_nv nv[28];
   size_t nnv = ARRLEN(nv);
   size_t i;