[ovs-dev] [threads 19/28] byteq: Make the queue size variable instead of fixed at BYTEQ_SIZE bytes.

[Ben Pfaff]

Signed-off-by: Ben Pfaff <b...@nicira.com>
---
 lib/byteq.c   |   26 +++++++++++++++-----------
 lib/byteq.h   |   10 ++++------
 lib/jsonrpc.c |    5 +++--
 3 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/lib/byteq.c b/lib/byteq.c
index 2ee4a65..3f865cf 100644
--- a/lib/byteq.c
+++ b/lib/byteq.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2008, 2009, 2012 Nicira, Inc.
+/* Copyright (c) 2008, 2009, 2012, 2013 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,13 +20,17 @@
 #include <unistd.h>
 #include "util.h"
 
-/* The queue size must be a power of 2. */
-BUILD_ASSERT_DECL(!(BYTEQ_SIZE & (BYTEQ_SIZE - 1)));
-
-/* Initializes 'q' as empty. */
+/* Initializes 'q' as an empty byteq that uses the 'size' bytes of 'buffer' to
+ * store data.  'size' must be a power of 2.
+ *
+ * The caller must ensure that 'buffer' remains available to the byteq as long
+ * as 'q' is in use. */
 void
-byteq_init(struct byteq *q)
+byteq_init(struct byteq *q, uint8_t *buffer, size_t size)
 {
+    ovs_assert(is_pow2(size));
+    q->buffer = buffer;
+    q->size = size;
     q->head = q->tail = 0;
 }
 
@@ -41,7 +45,7 @@ byteq_used(const struct byteq *q)
 int
 byteq_avail(const struct byteq *q)
 {
-    return BYTEQ_SIZE - byteq_used(q);
+    return q->size - byteq_used(q);
 }
 
 /* Returns true if no bytes are queued in 'q',
@@ -147,7 +151,7 @@ int
 byteq_tailroom(const struct byteq *q)
 {
     int used = byteq_used(q);
-    int tail_to_end = BYTEQ_SIZE - (q->tail & (BYTEQ_SIZE - 1));
+    int tail_to_end = q->size - (q->tail & (q->size - 1));
     return MIN(used, tail_to_end);
 }
 
@@ -156,7 +160,7 @@ byteq_tailroom(const struct byteq *q)
 const uint8_t *
 byteq_tail(const struct byteq *q)
 {
-    return &q->buffer[q->tail & (BYTEQ_SIZE - 1)];
+    return &q->buffer[q->tail & (q->size - 1)];
 }
 
 /* Removes 'n' bytes from the tail of 'q', which must have at least 'n' bytes
@@ -173,7 +177,7 @@ byteq_advance_tail(struct byteq *q, unsigned int n)
 uint8_t *
 byteq_head(struct byteq *q)
 {
-    return &q->buffer[q->head & (BYTEQ_SIZE - 1)];
+    return &q->buffer[q->head & (q->size - 1)];
 }
 
 /* Returns the number of contiguous bytes of free space starting at the head
@@ -182,7 +186,7 @@ int
 byteq_headroom(const struct byteq *q)
 {
     int avail = byteq_avail(q);
-    int head_to_end = BYTEQ_SIZE - (q->head & (BYTEQ_SIZE - 1));
+    int head_to_end = q->size - (q->head & (q->size - 1));
     return MIN(avail, head_to_end);
 }
 
diff --git a/lib/byteq.h b/lib/byteq.h
index 5fa51fd..d73e368 100644
--- a/lib/byteq.h
+++ b/lib/byteq.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2008, 2009 Nicira, Inc.
+/* Copyright (c) 2008, 2009, 2013 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,17 +20,15 @@
 #include <stddef.h>
 #include <stdint.h>
 
-/* Maximum number of bytes in a byteq. */
-#define BYTEQ_SIZE 512
-
 /* General-purpose circular queue of bytes. */
 struct byteq {
-    uint8_t buffer[BYTEQ_SIZE]; /* Circular queue. */
+    uint8_t *buffer;            /* Circular queue. */
+    unsigned int size;          /* Number of bytes allocated for 'buffer'. */
     unsigned int head;          /* Head of queue. */
     unsigned int tail;          /* Chases the head. */
 };
 
-void byteq_init(struct byteq *);
+void byteq_init(struct byteq *, uint8_t *buffer, size_t size);
 int byteq_used(const struct byteq *);
 int byteq_avail(const struct byteq *);
 bool byteq_is_empty(const struct byteq *);
diff --git a/lib/jsonrpc.c b/lib/jsonrpc.c
index 56b4cce..b4bbc84 100644
--- a/lib/jsonrpc.c
+++ b/lib/jsonrpc.c
@@ -41,6 +41,7 @@ struct jsonrpc {
 
     /* Input. */
     struct byteq input;
+    uint8_t input_buffer[512];
     struct json_parser *parser;
     struct jsonrpc_msg *received;
 
@@ -87,7 +88,7 @@ jsonrpc_open(struct stream *stream)
     rpc = xzalloc(sizeof *rpc);
     rpc->name = xstrdup(stream_get_name(stream));
     rpc->stream = stream;
-    byteq_init(&rpc->input);
+    byteq_init(&rpc->input, rpc->input_buffer, sizeof rpc->input_buffer);
     list_init(&rpc->output);
 
     return rpc;
@@ -330,7 +331,7 @@ jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
                 jsonrpc_received(rpc);
                 if (rpc->status) {
                     const struct byteq *q = &rpc->input;
-                    if (q->head <= BYTEQ_SIZE) {
+                    if (q->head <= q->size) {
                         stream_report_content(q->buffer, q->head,
                                               STREAM_JSONRPC,
                                               THIS_MODULE, rpc->name);
-- 
1.7.2.5

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