tdb: tdb_summary() support.

Autobuild-User: Rusty Russell <rusty@rustcorp.com.au>
Autobuild-Date: Wed Dec 29 10:12:05 CET 2010 on sn-devel-104

3 files changed, 195 insertions, 2 deletions

diff --git a/lib/tdb/common/check.c b/lib/tdb/common/check.c
index bbb566c6f7..3387fbd098 100644
--- a/lib/tdb/common/check.c
+++ b/lib/tdb/common/check.c
@@ -308,7 +308,7 @@ static bool tdb_check_free_record(struct tdb_context *tdb,
 }
 
 /* Slow, but should be very rare. */
-static size_t dead_space(struct tdb_context *tdb, tdb_off_t off)
+size_t tdb_dead_space(struct tdb_context *tdb, tdb_off_t off)
 {
 	size_t len;
 
@@ -406,7 +406,7 @@ _PUBLIC_ int tdb_check(struct tdb_context *tdb,
 				found_recovery = true;
 				break;
 			}
-			dead = dead_space(tdb, off);
+			dead = tdb_dead_space(tdb, off);
 			if (dead < sizeof(rec))
 				goto corrupt;
 
diff --git a/lib/tdb/common/summary.c b/lib/tdb/common/summary.c
new file mode 100644
index 0000000000..29959f9e5f
--- /dev/null
+++ b/lib/tdb/common/summary.c
@@ -0,0 +1,192 @@
+ /* 
+   Trivial Database: human-readable summary code
+   Copyright (C) Rusty Russell 2010
+   
+   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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+#include "tdb_private.h"
+
+#define SUMMARY_FORMAT \
+	"Size of file/data: %u/%zu\n" \
+	"Number of records: %zu\n" \
+	"Smallest/average/largest keys: %zu/%zu/%zu\n" \
+	"Smallest/average/largest data: %zu/%zu/%zu\n" \
+	"Smallest/average/largest padding: %zu/%zu/%zu\n" \
+	"Number of dead records: %zu\n" \
+	"Smallest/average/largest dead records: %zu/%zu/%zu\n" \
+	"Number of free records: %zu\n" \
+	"Smallest/average/largest free records: %zu/%zu/%zu\n" \
+	"Number of hash chains: %zu\n" \
+	"Smallest/average/largest hash chains: %zu/%zu/%zu\n" \
+	"Number of uncoalesced records: %zu\n" \
+	"Smallest/average/largest uncoalesced runs: %zu/%zu/%zu\n" \
+	"Percentage keys/data/padding/free/dead/rechdrs&tailers/hashes: %.0f/%.0f/%.0f/%.0f/%.0f/%.0f/%.0f\n"
+
+/* We don't use tally module, to keep upstream happy. */
+struct tally {
+	size_t min, max, total;
+	size_t num;
+};
+
+static void tally_init(struct tally *tally)
+{
+	tally->total = 0;
+	tally->num = 0;
+	tally->min = tally->max = 0;
+}
+
+static void tally_add(struct tally *tally, size_t len)
+{
+	if (tally->num == 0)
+		tally->max = tally->min = len;
+	else if (len > tally->max)
+		tally->max = len;
+	else if (len < tally->min)
+		tally->min = len;
+	tally->num++;
+	tally->total += len;
+}
+
+static size_t tally_mean(const struct tally *tally)
+{
+	if (!tally->num)
+		return 0;
+	return tally->total / tally->num;
+}
+
+static size_t get_hash_length(struct tdb_context *tdb, unsigned int i)
+{
+	tdb_off_t rec_ptr;
+	size_t count = 0;
+
+	if (tdb_ofs_read(tdb, TDB_HASH_TOP(i), &rec_ptr) == -1)
+		return 0;
+
+	/* keep looking until we find the right record */
+	while (rec_ptr) {
+		struct tdb_record r;
+		++count;
+		if (tdb_rec_read(tdb, rec_ptr, &r) == -1)
+			return 0;
+		rec_ptr = r.next;
+	}
+	return count;
+}
+
+_PUBLIC_ char *tdb_summary(struct tdb_context *tdb)
+{
+	tdb_off_t off;
+	struct tally freet, keys, data, dead, extra, hash, uncoal;
+	struct tdb_record rec;
+	char *ret = NULL;
+	bool locked;
+	size_t len, unc = 0;
+
+	/* Read-only databases use no locking at all: it's best-effort.
+	 * We may have a write lock already, so skip that case too. */
+	if (tdb->read_only || tdb->allrecord_lock.count != 0) {
+		locked = false;
+	} else {
+		if (tdb_lockall_read(tdb) == -1)
+			return NULL;
+		locked = true;
+	}
+
+	tally_init(&freet);
+	tally_init(&keys);
+	tally_init(&data);
+	tally_init(&dead);
+	tally_init(&extra);
+	tally_init(&hash);
+	tally_init(&uncoal);
+
+	for (off = TDB_DATA_START(tdb->header.hash_size);
+	     off < tdb->map_size - 1;
+	     off += sizeof(rec) + rec.rec_len) {
+		if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec),
+					   DOCONV()) == -1)
+			goto unlock;
+		switch (rec.magic) {
+		case TDB_MAGIC:
+			tally_add(&keys, rec.key_len);
+			tally_add(&data, rec.data_len);
+			tally_add(&extra, rec.rec_len - (rec.key_len
+							 + rec.data_len));
+			if (unc > 1)
+				tally_add(&uncoal, unc - 1);
+			unc = 0;
+			break;
+		case TDB_FREE_MAGIC:
+			tally_add(&freet, rec.rec_len);
+			unc++;
+			break;
+		/* If we crash after ftruncate, we can get zeroes or fill. */
+		case TDB_RECOVERY_INVALID_MAGIC:
+		case 0x42424242:
+			unc++;
+			rec.rec_len = tdb_dead_space(tdb, off) - sizeof(rec);
+			/* Fall through */
+		case TDB_DEAD_MAGIC:
+			tally_add(&dead, rec.rec_len);
+			break;
+		default:
+			TDB_LOG((tdb, TDB_DEBUG_ERROR,
+				 "Unexpected record magic 0x%x at offset %d\n",
+				 rec.magic, off));
+			goto unlock;
+		}
+	}
+	if (unc > 1)
+		tally_add(&uncoal, unc - 1);
+
+	for (off = 0; off < tdb->header.hash_size; off++)
+		tally_add(&hash, get_hash_length(tdb, off));
+
+	/* 20 is max length of a %zu. */
+	len = strlen(SUMMARY_FORMAT) + 35*20 + 1;
+	ret = malloc(len);
+	if (!ret)
+		goto unlock;
+
+	sprintf(ret, SUMMARY_FORMAT,
+		tdb->map_size, keys.total+data.total,
+		keys.num,
+		keys.min, tally_mean(&keys), keys.max,
+		data.min, tally_mean(&data), data.max,
+		extra.min, tally_mean(&extra), extra.max,
+		dead.num,
+		dead.min, tally_mean(&dead), dead.max,
+		freet.num,
+		freet.min, tally_mean(&freet), freet.max,
+		hash.num,
+		hash.min, tally_mean(&hash), hash.max,
+		uncoal.total,
+		uncoal.min, tally_mean(&uncoal), uncoal.max,
+		keys.total * 100.0 / tdb->map_size,
+		data.total * 100.0 / tdb->map_size,
+		extra.total * 100.0 / tdb->map_size,
+		freet.total * 100.0 / tdb->map_size,
+		dead.total * 100.0 / tdb->map_size,
+		(keys.num + freet.num + dead.num)
+		* (sizeof(struct tdb_record) + sizeof(uint32_t))
+		* 100.0 / tdb->map_size,
+		tdb->header.hash_size * sizeof(tdb_off_t)
+		* 100.0 / tdb->map_size);
+
+unlock:
+	if (locked) {
+		tdb_unlockall_read(tdb);
+	}
+	return ret;
+}
diff --git a/lib/tdb/common/tdb_private.h b/lib/tdb/common/tdb_private.h
index 0c621636fa..0186fb9530 100644
--- a/lib/tdb/common/tdb_private.h
+++ b/lib/tdb/common/tdb_private.h
@@ -274,3 +274,4 @@ int tdb_transaction_recover(struct tdb_context *tdb);
 void tdb_header_hash(struct tdb_context *tdb,
 		     uint32_t *magic1_hash, uint32_t *magic2_hash);
 unsigned int tdb_old_hash(TDB_DATA *key);
+size_t tdb_dead_space(struct tdb_context *tdb, tdb_off_t off);