From 117f11fd62a7541704e600ab2a9821f3f9e91395 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 4 Jul 2019 07:20:40 -0700
Subject: sha256: recycle I/O buffer used in stream hash.

* chksum.c (sha256_stream): Use iobuf_get and iobuf_put.

* gc.c (gc): Do not mark the list of recycled buffers; just
consider them to be garbage and clear the list, like we do
with recycled conses via rcyc_empty.

* stream.c (iobuf_free_list): New static variable.
(iobuf_get, iobuf_put, iobuf_list_empty): New functions.

* stream.h (iobuf_get, iobuf_put, iobuf_list_empty): Declared.
---
 chksum.c |  5 +++--
 gc.c     |  1 +
 stream.c | 27 +++++++++++++++++++++++++++
 stream.h |  4 +++-
 4 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/chksum.c b/chksum.c
index 588bdf92..1863ba47 100644
--- a/chksum.c
+++ b/chksum.c
@@ -51,8 +51,8 @@ val sha256_stream(val stream, val nbytes)
 {
   SHA256_t s256;
   unsigned char *hash = chk_malloc(SHA256_DIGEST_LENGTH);
-  val bfsz = num_fast(BUFSIZ);
-  val buf = make_buf(bfsz, nil, nil);
+  val buf = iobuf_get();
+  val bfsz = length_buf(buf);
   SHA256_init(&s256);
 
   if (null_or_missing_p(nbytes)) {
@@ -88,6 +88,7 @@ val sha256_stream(val stream, val nbytes)
   }
 
   SHA256_final(&s256, hash);
+  iobuf_put(buf);
   return make_borrowed_buf(num_fast(SHA256_DIGEST_LENGTH), hash);
 }
 
diff --git a/gc.c b/gc.c
index 178e1cc6..4c8d9f6d 100644
--- a/gc.c
+++ b/gc.c
@@ -754,6 +754,7 @@ void gc(void)
   save_context(mc);
   gc_enabled = 0;
   rcyc_empty();
+  iobuf_list_empty();
   mark(&mc, &gc_stack_top);
   hash_process_weak();
   prepare_finals();
diff --git a/stream.c b/stream.c
index ec9a7f66..4cad323d 100644
--- a/stream.c
+++ b/stream.c
@@ -4605,6 +4605,33 @@ val make_byte_input_stream(val obj)
   }
 }
 
+static val iobuf_free_list;
+
+val iobuf_get(void)
+{
+  val buf = iobuf_free_list;
+
+  if (buf) {
+    val next = buf->b.len;
+    buf->b.len = buf->b.size;
+    iobuf_free_list = next;
+    return buf;
+  } else {
+    return make_buf(num_fast(BUFSIZ), nil, nil);
+  }
+}
+
+void iobuf_put(val buf)
+{
+  buf->b.len = iobuf_free_list;
+  iobuf_free_list = buf;
+}
+
+void iobuf_list_empty(void)
+{
+  iobuf_free_list = nil;
+}
+
 void stream_init(void)
 {
   prot1(&ap_regex);
diff --git a/stream.h b/stream.h
index 2887b305..bc83122c 100644
--- a/stream.h
+++ b/stream.h
@@ -240,5 +240,7 @@ val base_name(val path);
 val dir_name(val path);
 val path_cat(val dir_name, val base_name);
 val make_byte_input_stream(val obj);
-
+val iobuf_get(void);
+void iobuf_put(val buf);
+void iobuf_list_empty(void);
 void stream_init(void);
-- 
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