From d4350788eea01f04b464d382d74ee0f391a78398 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Mon, 25 Nov 2019 13:03:37 +0000
Subject:  Initial libdcache implementation

---
 src/caches/dcache_add.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 src/caches/dcache_add.c

(limited to 'src/caches/dcache_add.c')

diff --git a/src/caches/dcache_add.c b/src/caches/dcache_add.c
new file mode 100644
index 0000000..a534f7a
--- /dev/null
+++ b/src/caches/dcache_add.c
@@ -0,0 +1,110 @@
+/* ISC license. */
+
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+#include <skalibs/uint64.h>
+#include <skalibs/alloc.h>
+#include <skalibs/tai.h>
+#include <skalibs/gensetdyn.h>
+#include <skalibs/avlnode.h>
+#include <skalibs/avltree.h>
+
+#include <s6-dns/dcache.h>
+
+#define DNODE(z, i) GENSETDYN_P(dcache_node_t, &(z)->storage, i)
+#define DCACHE_NODE_OVERHEAD (32 + sizeof(dcache_node_t) + 3 * sizeof(avlnode))
+
+static void uniquify (avltree const *tree, tain_t *stamp)
+{
+  static tain_t const nano = { .sec = TAI_ZERO, .nano = 1 } ;
+  uint32_t dummy ;
+  while (avltree_search(tree, stamp, &dummy))
+    tain_add(stamp, stamp, &nano) ;
+}
+
+static void dcache_delete (dcache_t *z, uint32_t i)
+{
+  dcache_node_t *y = DNODE(z, i) ;
+  avltree_delete(&z->by_expire, &y->expire) ;
+  avltree_delete(&z->by_entry, &y->entry) ;
+  avltree_delete(&z->by_key, &y->key) ;
+  alloc_free(y->key.s) ;
+  z->size -= DCACHE_NODE_OVERHEAD + y->key.len + y->datalen ;
+  gensetdyn_delete(&z->storage, i) ;
+}
+
+static inline void dcache_gc_by_entry (dcache_t *z, uint64_t max)
+{
+  while (z->size > max)
+  {
+    uint32_t oldest ;
+    if (!avltree_min(&z->by_entry, &oldest)) break ;
+    dcache_delete(z, oldest) ;
+  }
+}
+
+static inline void dcache_gc_by_expire (dcache_t *z, tain_t const *stamp)
+{
+  for (;;)
+  {
+    uint32_t i ;
+    if (!avltree_min(&z->by_expire, &i)) break ;
+    if (tain_less(stamp, &DNODE(z, i)->expire)) break ;
+    dcache_delete(z, i) ;
+  }
+}
+
+static inline int dcache_add_node (dcache_t *z, dcache_node_t const *node)
+{
+  uint32_t i ;
+  dcache_node_t *y ;
+  if (!gensetdyn_new(&z->storage, &i)) return 0 ;
+  y = DNODE(z, i) ; *y = *node ;
+  uniquify(&z->by_entry, &y->entry) ;
+  uniquify(&z->by_expire, &y->expire) ;
+  if (!avltree_insert(&z->by_key, i)) goto err1 ;
+  if (!avltree_insert(&z->by_entry, i)) goto err2 ;
+  if (!avltree_insert(&z->by_expire, i)) goto err3 ;
+  return 1 ;
+
+ err3:
+  avltree_delete(&z->by_entry, &y->entry) ;
+ err2:
+  avltree_delete(&z->by_key, &y->key) ;
+ err1:
+  gensetdyn_delete(&z->storage, i) ;
+  return 0 ;
+}
+
+static inline int dcache_add_unbounded (dcache_t *z, char const *key, uint16_t keylen, char const *data, uint16_t datalen, tain_t const *expire, tain_t const *stamp)
+{
+  uint32_t len = keylen + datalen ;
+  dcache_node_t y = { .key = { .s = alloc(len) } } ;
+  if (!y.key.s) return 0 ;
+  memcpy(y.key.s, key, keylen) ;
+  memcpy(y.key.s + keylen, data, datalen) ;
+  y.key.len = keylen ;
+  y.datalen = datalen ;
+  y.entry = *stamp ;
+  y.expire = *expire ;
+  if (!dcache_add_node(z, &y))
+  {
+    alloc_free(y.key.s) ;
+    return 0 ;
+  }
+  z->size += DCACHE_NODE_OVERHEAD + len ;
+  z->motion += DCACHE_NODE_OVERHEAD + len ;
+  return 1 ;
+}
+
+
+int dcache_add (dcache_t *z, uint64_t max, char const *key, uint16_t keylen, char const *data, uint16_t datalen, tain_t const *expire, tain_t const *stamp)
+{
+  uint64_t size = DCACHE_NODE_OVERHEAD + keylen + datalen ;
+  if (size > max) return (errno = EINVAL, 0) ;
+  if (z->size > max - size) dcache_gc_by_expire(z, stamp) ;
+  if (z->size > max - size) dcache_gc_by_entry(z, max - size) ;
+  return dcache_add_unbounded(z, key, keylen, data, datalen, expire, stamp) ;
+}
-- 
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