X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash-mm-mmap.c;fp=rculfhash-mm-mmap.c;h=542c884e9f576c4dae45186b4fa0b4849cbd4eb8;hp=0000000000000000000000000000000000000000;hb=b0b5525153fce8abae07b9573da1d5169e02eb2b;hpb=308d1cb3650b63d373e60eef0582d6e238b0d2d0

diff --git a/rculfhash-mm-mmap.c b/rculfhash-mm-mmap.c
new file mode 100644
index 0000000..542c884
--- /dev/null
+++ b/rculfhash-mm-mmap.c
@@ -0,0 +1,160 @@
+/*
+ * rculfhash-mm-mmap.c
+ *
+ * mmap/reservation based memory management for Lock-Free RCU Hash Table
+ *
+ * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <unistd.h>
+#include <sys/mman.h>
+#include "rculfhash-internal.h"
+
+/* reserve inaccessible memory space without allocation any memory */
+static void *memory_map(size_t length)
+{
+	void *ret = mmap(NULL, length, PROT_NONE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	assert(ret != MAP_FAILED);
+	return ret;
+}
+
+static void memory_unmap(void *ptr, size_t length)
+{
+	int ret = munmap(ptr, length);
+
+	assert(ret == 0);
+}
+
+static void memory_populate(void *ptr, size_t length)
+{
+	void *ret = mmap(ptr, length, PROT_READ | PROT_WRITE,
+			MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	assert(ret == ptr);
+}
+
+/*
+ * Discard garbage memory and avoid system save it when try to swap it out.
+ * Make it still reserved, inaccessible.
+ */
+static void memory_discard(void *ptr, size_t length)
+{
+	void *ret = mmap(ptr, length, PROT_NONE,
+			MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	assert(ret == ptr);
+}
+
+static
+void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
+{
+	if (order == 0) {
+		if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
+			/* small table */
+			ht->tbl_mmap = calloc(ht->max_nr_buckets,
+					sizeof(*ht->tbl_mmap));
+			assert(ht->tbl_mmap);
+			return;
+		}
+		/* large table */
+		ht->tbl_mmap = memory_map(ht->max_nr_buckets
+			* sizeof(*ht->tbl_mmap));
+		memory_populate(ht->tbl_mmap,
+			ht->min_nr_alloc_buckets * sizeof(*ht->tbl_mmap));
+	} else if (order > ht->min_alloc_buckets_order) {
+		/* large table */
+		unsigned long len = 1UL << (order - 1);
+
+		assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
+		memory_populate(ht->tbl_mmap + len,
+				len * sizeof(*ht->tbl_mmap));
+	}
+	/* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
+}
+
+/*
+ * cds_lfht_free_bucket_table() should be called with decreasing order.
+ * When cds_lfht_free_bucket_table(0) is called, it means the whole
+ * lfht is destroyed.
+ */
+static
+void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
+{
+	if (order == 0) {
+		if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
+			/* small table */
+			poison_free(ht->tbl_mmap);
+			return;
+		}
+		/* large table */
+		memory_unmap(ht->tbl_mmap,
+			ht->max_nr_buckets * sizeof(*ht->tbl_mmap));
+	} else if (order > ht->min_alloc_buckets_order) {
+		/* large table */
+		unsigned long len = 1UL << (order - 1);
+
+		assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
+		memory_discard(ht->tbl_mmap + len, len * sizeof(*ht->tbl_mmap));
+	}
+	/* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
+}
+
+static
+struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
+{
+	return &ht->tbl_mmap[index];
+}
+
+static
+struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
+		unsigned long max_nr_buckets)
+{
+	struct cds_lfht *ht;
+	unsigned long page_bucket_size = getpagesize() / sizeof(*ht->tbl_mmap);
+
+	if (max_nr_buckets <= page_bucket_size) {
+		/* small table */
+		min_nr_alloc_buckets = max_nr_buckets;
+	} else {
+		/* large table */
+		min_nr_alloc_buckets = max(min_nr_alloc_buckets,
+					page_bucket_size);
+	}
+
+	ht = calloc(1, sizeof(struct cds_lfht));
+	assert(ht);
+
+	ht->mm = &cds_lfht_mm_mmap;
+
+	ht->min_nr_alloc_buckets = min_nr_alloc_buckets;
+	ht->min_alloc_buckets_order =
+			get_count_order_ulong(min_nr_alloc_buckets);
+	ht->max_nr_buckets = max_nr_buckets;
+
+	ht->bucket_at = bucket_at;
+
+	return ht;
+}
+
+const struct cds_lfht_mm_type cds_lfht_mm_mmap = {
+	.alloc_cds_lfht = alloc_cds_lfht,
+	.alloc_bucket_table = cds_lfht_alloc_bucket_table,
+	.free_bucket_table = cds_lfht_free_bucket_table,
+	.bucket_at = bucket_at,
+};