X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb2%2Ffree.c;h=48ea2b20185d8d6fbbeb737657331d666cffb6dd;hp=13db5933911073577e42d1175fcecd5b7da12efb;hb=96b169e986cda1de9ffbbdc98042e1099515ca34;hpb=5e30abc662990449444769c71cf98ca788db4117

diff --git a/ccan/tdb2/free.c b/ccan/tdb2/free.c
index 13db5933..48ea2b20 100644
--- a/ccan/tdb2/free.c
+++ b/ccan/tdb2/free.c
@@ -105,7 +105,7 @@ static tdb_off_t find_free_head(struct tdb_context *tdb,
 /* Remove from free bucket. */
 static int remove_from_list(struct tdb_context *tdb,
 			    tdb_off_t b_off, tdb_off_t r_off,
-			    struct tdb_free_record *r)
+			    const struct tdb_free_record *r)
 {
 	tdb_off_t off;
 
@@ -244,12 +244,15 @@ static size_t record_leftover(size_t keylen, size_t datalen,
 	return leftover;
 }
 
-/* FIXME: Shortcut common case where tdb->flist == flist */
 static tdb_off_t flist_offset(struct tdb_context *tdb, unsigned int flist)
 {
-	tdb_off_t off = first_flist(tdb);
+	tdb_off_t off;
 	unsigned int i;
 
+	if (likely(tdb->flist == flist))
+		return tdb->flist_off;
+
+	off = first_flist(tdb);
 	for (i = 0; i < flist; i++)
 		off = next_flist(tdb, off);
 	return off;
@@ -259,90 +262,95 @@ static tdb_off_t flist_offset(struct tdb_context *tdb, unsigned int flist)
 static int coalesce(struct tdb_context *tdb,
 		    tdb_off_t off, tdb_off_t b_off, tdb_len_t data_len)
 {
-	struct tdb_free_record pad, *r;
 	tdb_off_t end;
+	struct tdb_free_record rec;
 
+	add_stat(tdb, alloc_coalesce_tried, 1);
 	end = off + sizeof(struct tdb_used_record) + data_len;
 
 	while (end < tdb->map_size) {
+		const struct tdb_free_record *r;
 		tdb_off_t nb_off;
 		unsigned flist, bucket;
 
-		/* FIXME: do tdb_get here and below really win? */
-		r = tdb_get(tdb, end, &pad, sizeof(pad));
+		r = tdb_access_read(tdb, end, sizeof(*r), true);
 		if (!r)
 			goto err;
 
-		if (frec_magic(r) != TDB_FREE_MAGIC)
+		if (frec_magic(r) != TDB_FREE_MAGIC) {
+			tdb_access_release(tdb, r);
 			break;
+		}
 
 		flist = frec_flist(r);
 		bucket = size_to_bucket(frec_len(r));
 		nb_off = bucket_off(flist_offset(tdb, flist), bucket);
+		tdb_access_release(tdb, r);
 
 		/* We may be violating lock order here, so best effort. */
-		if (tdb_lock_free_bucket(tdb, nb_off, TDB_LOCK_NOWAIT) == -1)
+		if (tdb_lock_free_bucket(tdb, nb_off, TDB_LOCK_NOWAIT) == -1) {
+			add_stat(tdb, alloc_coalesce_lockfail, 1);
 			break;
+		}
 
 		/* Now we have lock, re-check. */
-		r = tdb_get(tdb, end, &pad, sizeof(pad));
-		if (!r) {
+		if (tdb_read_convert(tdb, end, &rec, sizeof(rec))) {
 			tdb_unlock_free_bucket(tdb, nb_off);
 			goto err;
 		}
 
-		if (unlikely(frec_magic(r) != TDB_FREE_MAGIC)) {
+		if (unlikely(frec_magic(&rec) != TDB_FREE_MAGIC)) {
+			add_stat(tdb, alloc_coalesce_race, 1);
 			tdb_unlock_free_bucket(tdb, nb_off);
 			break;
 		}
 
-		if (unlikely(frec_flist(r) != flist)
-		    || unlikely(size_to_bucket(frec_len(r)) != bucket)) {
+		if (unlikely(frec_flist(&rec) != flist)
+		    || unlikely(size_to_bucket(frec_len(&rec)) != bucket)) {
+			add_stat(tdb, alloc_coalesce_race, 1);
 			tdb_unlock_free_bucket(tdb, nb_off);
 			break;
 		}
 
-		if (remove_from_list(tdb, nb_off, end, r) == -1) {
+		if (remove_from_list(tdb, nb_off, end, &rec) == -1) {
 			tdb_unlock_free_bucket(tdb, nb_off);
 			goto err;
 		}
 
-		end += sizeof(struct tdb_used_record) + frec_len(r);
+		end += sizeof(struct tdb_used_record) + frec_len(&rec);
 		tdb_unlock_free_bucket(tdb, nb_off);
+		add_stat(tdb, alloc_coalesce_num_merged, 1);
 	}
 
 	/* Didn't find any adjacent free? */
 	if (end == off + sizeof(struct tdb_used_record) + data_len)
 		return 0;
 
-	/* OK, expand record */
-	r = tdb_get(tdb, off, &pad, sizeof(pad));
-	if (!r)
+	/* OK, expand initial record */
+	if (tdb_read_convert(tdb, off, &rec, sizeof(rec)))
 		goto err;
 
-	if (frec_len(r) != data_len) {
+	if (frec_len(&rec) != data_len) {
 		tdb->ecode = TDB_ERR_CORRUPT;
 		tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 			 "coalesce: expected data len %llu not %llu\n",
-			 (long long)data_len, (long long)frec_len(r));
+			 (long long)data_len, (long long)frec_len(&rec));
 		goto err;
 	}
 
-	if (remove_from_list(tdb, b_off, off, r) == -1)
-		goto err;
-
-	r = tdb_access_write(tdb, off, sizeof(*r), true);
-	if (!r)
+	if (remove_from_list(tdb, b_off, off, &rec) == -1)
 		goto err;
 
 	/* We have to drop this to avoid deadlocks, so make sure record
 	 * doesn't get coalesced by someone else! */
-	r->magic_and_prev = TDB_COALESCING_MAGIC << (64 - TDB_OFF_UPPER_STEAL);
+	rec.magic_and_prev = TDB_COALESCING_MAGIC
+		<< (64 - TDB_OFF_UPPER_STEAL);
 	/* FIXME: Use 255 as invalid free list? */
-	r->flist_and_len = end - off - sizeof(struct tdb_used_record);
-	if (tdb_access_commit(tdb, r) != 0)
+	rec.flist_and_len = end - off - sizeof(struct tdb_used_record);
+	if (tdb_write_convert(tdb, off, &rec, sizeof(rec)) != 0)
 		goto err;
 
+	add_stat(tdb, alloc_coalesce_succeeded, 1);
 	tdb_unlock_free_bucket(tdb, b_off);
 
 	if (add_free_record(tdb, off, end - off) == -1)
@@ -364,10 +372,11 @@ static tdb_off_t lock_and_alloc(struct tdb_context *tdb,
 				unsigned hashlow)
 {
 	tdb_off_t off, b_off,best_off;
-	struct tdb_free_record pad, best = { 0 }, *r;
+	struct tdb_free_record best = { 0 };
 	double multiplier;
 	size_t size = adjust_size(keylen, datalen);
 
+	add_stat(tdb, allocs, 1);
 again:
 	b_off = bucket_off(flist_off, bucket);
 
@@ -393,12 +402,16 @@ again:
 		goto unlock_err;
 
 	while (off) {
-		/* FIXME: Does tdb_get win anything here? */
-		r = tdb_get(tdb, off, &pad, sizeof(*r));
+		const struct tdb_free_record *r;
+		tdb_len_t len;
+		tdb_off_t next;
+
+		r = tdb_access_read(tdb, off, sizeof(*r), true);
 		if (!r)
 			goto unlock_err;
 
 		if (frec_magic(r) != TDB_FREE_MAGIC) {
+			tdb_access_release(tdb, r);
 			tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 				 "lock_and_alloc: %llu non-free 0x%llx\n",
 				 (long long)off, (long long)r->magic_and_prev);
@@ -410,13 +423,19 @@ again:
 			best = *r;
 		}
 
-		if (frec_len(&best) < size * multiplier && best_off)
+		if (frec_len(&best) < size * multiplier && best_off) {
+			tdb_access_release(tdb, r);
 			break;
+		}
 
 		multiplier *= 1.01;
 
+		next = r->next;
+		len = frec_len(r);
+		tdb_access_release(tdb, r);
+
 		/* Since we're going slow anyway, try coalescing here. */
-		switch (coalesce(tdb, off, b_off, frec_len(r))) {
+		switch (coalesce(tdb, off, b_off, len)) {
 		case -1:
 			/* This has already unlocked on error. */
 			return -1;
@@ -424,7 +443,7 @@ again:
 			/* This has unlocked list, restart. */
 			goto again;
 		}
-		off = r->next;
+		off = next;
 	}
 
 	/* If we found anything at all, use it. */
@@ -450,15 +469,18 @@ again:
 		if (tdb_write_convert(tdb, best_off, &rec, sizeof(rec)) != 0)
 			goto unlock_err;
 
-		tdb_unlock_free_bucket(tdb, b_off);
-
+		/* Bucket of leftover will be <= current bucket, so nested
+		 * locking is allowed. */
 		if (leftover) {
+			add_stat(tdb, alloc_leftover, 1);
 			if (add_free_record(tdb,
 					    best_off + sizeof(rec)
 					    + frec_len(&best) - leftover,
 					    leftover))
-				return TDB_OFF_ERR;
+				best_off = TDB_OFF_ERR;
 		}
+		tdb_unlock_free_bucket(tdb, b_off);
+
 		return best_off;
 	}
 
@@ -500,6 +522,10 @@ static tdb_off_t get_free(struct tdb_context *tdb,
 			if (off == TDB_OFF_ERR)
 				return TDB_OFF_ERR;
 			if (off != 0) {
+				if (b == start_b)
+					add_stat(tdb, alloc_bucket_exact, 1);
+				if (b == TDB_FREE_BUCKETS - 1)
+					add_stat(tdb, alloc_bucket_max, 1);
 				/* Worked?  Stay using this list. */
 				tdb->flist_off = flist_off;
 				tdb->flist = flist;
@@ -511,6 +537,7 @@ static tdb_off_t get_free(struct tdb_context *tdb,
 		/* Hmm, try next list. */
 		flist_off = next_flist(tdb, flist_off);
 		flist++;
+
 		if (flist_off == 0) {
 			wrapped = true;
 			flist_off = first_flist(tdb);
@@ -566,6 +593,14 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
 		return -1;
 	}
 
+	/* always make room for at least 100 more records, and at
+           least 25% more space. */
+	if (size * TDB_EXTENSION_FACTOR > tdb->map_size / 4)
+		wanted = size * TDB_EXTENSION_FACTOR;
+	else
+		wanted = tdb->map_size / 4;
+	wanted = adjust_size(0, wanted);
+
 	/* Only one person can expand file at a time. */
 	if (tdb_lock_expand(tdb, F_WRLCK) != 0)
 		return -1;
@@ -578,7 +613,7 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
 		return 0;
 	}
 
-	if (tdb->methods->expand_file(tdb, wanted*TDB_EXTENSION_FACTOR) == -1) {
+	if (tdb->methods->expand_file(tdb, wanted) == -1) {
 		tdb_unlock_expand(tdb, F_WRLCK);
 		return -1;
 	}
@@ -586,7 +621,8 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
 	/* We need to drop this lock before adding free record. */
 	tdb_unlock_expand(tdb, F_WRLCK);
 
-	return add_free_record(tdb, old_size, wanted * TDB_EXTENSION_FACTOR);
+	add_stat(tdb, expands, 1);
+	return add_free_record(tdb, old_size, wanted);
 }
 
 /* This won't fail: it will expand the database if it has to. */