tdb2: implement tdb_exists and tdb_parse_record

These are the same as the TDB1 functions; but note that there is no reliable
way to tell if tdb_exists() fails due to an error.  This simplifies the API,
but means you have to use tdb_fetch() if you really care. 

ccan/tdb2/tdb.c

@@ -243,6 +243,21 @@ enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
 	return ecode;
 }
 
+bool tdb_exists(struct tdb_context *tdb, TDB_DATA key)
+{
+	tdb_off_t off;
+	struct tdb_used_record rec;
+	struct hash_info h;
+
+	off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
+	if (TDB_OFF_IS_ERR(off)) {
+		return false;
+	}
+	tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
+
+	return off ? true : false;
+}
+
 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 {
 	tdb_off_t off;
@@ -377,3 +392,42 @@ enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
 	errno = saved_errno;
 	return ecode;
 }
+
+enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
+				 TDB_DATA key,
+				 enum TDB_ERROR (*parse)(TDB_DATA key,
+							 TDB_DATA data,
+							 void *p),
+				 void *p)
+{
+	tdb_off_t off;
+	struct tdb_used_record rec;
+	struct hash_info h;
+	TDB_DATA data;
+	enum TDB_ERROR ecode;
+
+	off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
+	if (TDB_OFF_IS_ERR(off)) {
+		return off;
+	}
+
+	if (!off) {
+		ecode = TDB_ERR_NOEXIST;
+	} else {
+		data.dsize = rec_data_length(&rec);
+		data.dptr = (void *)tdb_access_read(tdb,
+						    off + sizeof(rec)
+						    + key.dsize,
+						    data.dsize, false);
+		if (TDB_PTR_IS_ERR(data.dptr)) {
+			ecode = TDB_PTR_ERR(data.dptr);
+		} else {
+			ecode = parse(key, data, p);
+			tdb_access_release(tdb, data.dptr);
+		}
+	}
+
+	tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
+	return ecode;
+}
+

ccan/tdb2/tdb2.h

@@ -38,6 +38,8 @@ extern "C" {
 #include <signal.h>
 /* For uint64_t */
 #include <stdint.h>
+/* For bool */
+#include <stdbool.h>
 #endif
 #include <ccan/compiler/compiler.h>
 #include <ccan/typesafe_cb/typesafe_cb.h>
@@ -197,6 +199,15 @@ enum TDB_ERROR tdb_append(struct tdb_context *tdb,
  */
 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key);
 
+/**
+ * tdb_exists - does a key exist in the database?
+ * @tdb: the tdb context returned from tdb_open()
+ * @key: the key to search for.
+ *
+ * Returns true if it exists, or false if it doesn't or any other error.
+ */
+bool tdb_exists(struct tdb_context *tdb, TDB_DATA key);
+
 /**
  * tdb_transaction_start - start a transaction
  * @tdb: the tdb context returned from tdb_open()
@@ -276,6 +287,30 @@ int64_t tdb_traverse_(struct tdb_context *tdb,
 		      int (*fn)(struct tdb_context *,
 				TDB_DATA, TDB_DATA, void *), void *p);
 
+/**
+ * tdb_parse_record - operate directly on data in the database.
+ * @tdb: the tdb context returned from tdb_open()
+ * @key: the key whose record we should hand to @parse
+ * @parse: the function to call for the data
+ * @p: the private pointer to hand to @parse (types must match).
+ *
+ * This avoids a copy for many cases, by handing you a pointer into
+ * the memory-mapped database.  It also locks the record to prevent
+ * other accesses at the same time.
+ *
+ * Do not alter the data handed to parse()!
+ */
+#define tdb_parse_record(tdb, key, parse, p)				\
+	tdb_parse_record_((tdb), (key),					\
+			  typesafe_cb_preargs(enum TDB_ERROR, (parse), (p), \
+					      TDB_DATA, TDB_DATA), (p))
+
+enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
+				 TDB_DATA key,
+				 enum TDB_ERROR (*parse)(TDB_DATA key,
+							 TDB_DATA data,
+							 void *p),
+				 void *p);
 /**
  * tdb_firstkey - get the "first" key in a TDB
  * @tdb: the tdb context returned from tdb_open()
@@ -328,6 +363,15 @@ enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
  */
 enum TDB_ERROR tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
 
+/**
+ * tdb_wipe_all - wipe the database clean
+ * @tdb: the tdb context returned from tdb_open()
+ *
+ * Completely erase the database.  This is faster than iterating through
+ * each key and doing tdb_delete.
+ */
+enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb);
+
 /**
  * tdb_check - check a TDB for consistency
  * @tdb: the tdb context returned from tdb_open()

ccan/tdb2/test/run-14-exists.c

+#include <ccan/tdb2/tdb.c>
+#include <ccan/tdb2/open.c>
+#include <ccan/tdb2/free.c>
+#include <ccan/tdb2/lock.c>
+#include <ccan/tdb2/io.c>
+#include <ccan/tdb2/hash.c>
+#include <ccan/tdb2/check.c>
+#include <ccan/tdb2/transaction.c>
+#include <ccan/tap/tap.h>
+#include "logging.h"
+
+static bool test_records(struct tdb_context *tdb)
+{
+	int i;
+	struct tdb_data key = { (unsigned char *)&i, sizeof(i) };
+	struct tdb_data data = { (unsigned char *)&i, sizeof(i) };
+
+	for (i = 0; i < 1000; i++) {
+		if (tdb_exists(tdb, key))
+			return false;
+		if (tdb_store(tdb, key, data, TDB_REPLACE) != 0)
+			return false;
+		if (!tdb_exists(tdb, key))
+			return false;
+	}
+
+	for (i = 0; i < 1000; i++) {
+		if (!tdb_exists(tdb, key))
+			return false;
+		if (tdb_delete(tdb, key) != 0)
+			return false;
+		if (tdb_exists(tdb, key))
+			return false;
+	}
+	return true;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	struct tdb_context *tdb;
+	int flags[] = { TDB_INTERNAL, TDB_DEFAULT, TDB_NOMMAP,
+			TDB_INTERNAL|TDB_CONVERT, TDB_CONVERT,
+			TDB_NOMMAP|TDB_CONVERT };
+
+	plan_tests(sizeof(flags) / sizeof(flags[0]) * 2 + 1);
+	for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+		tdb = tdb_open("run-14-exists.tdb", flags[i],
+			       O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+		if (ok1(tdb))
+			ok1(test_records(tdb));
+		tdb_close(tdb);
+	}
+
+	ok1(tap_log_messages == 0);
+	return exit_status();
+}

ccan/tdb2/test/run-16-wipe_all.c

+#include <ccan/tdb2/tdb.c>
+#include <ccan/tdb2/open.c>
+#include <ccan/tdb2/free.c>
+#include <ccan/tdb2/lock.c>
+#include <ccan/tdb2/io.c>
+#include <ccan/tdb2/hash.c>
+#include <ccan/tdb2/check.c>
+#include <ccan/tdb2/transaction.c>
+#include <ccan/tdb2/traverse.c>
+#include <ccan/tap/tap.h>
+#include "logging.h"
+
+static bool add_records(struct tdb_context *tdb)
+{
+	int i;
+	struct tdb_data key = { (unsigned char *)&i, sizeof(i) };
+	struct tdb_data data = { (unsigned char *)&i, sizeof(i) };
+
+	for (i = 0; i < 1000; i++) {
+		if (tdb_store(tdb, key, data, TDB_REPLACE) != 0)
+			return false;
+	}
+	return true;
+}
+
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	struct tdb_context *tdb;
+	int flags[] = { TDB_INTERNAL, TDB_DEFAULT, TDB_NOMMAP,
+			TDB_INTERNAL|TDB_CONVERT, TDB_CONVERT,
+			TDB_NOMMAP|TDB_CONVERT };
+
+	plan_tests(sizeof(flags) / sizeof(flags[0]) * 4 + 1);
+	for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+		tdb = tdb_open("run-16-wipe_all.tdb", flags[i],
+			       O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+		if (ok1(tdb)) {
+			struct tdb_data key;
+			ok1(add_records(tdb));
+			ok1(tdb_wipe_all(tdb) == TDB_SUCCESS);
+			ok1(tdb_firstkey(tdb, &key) == TDB_ERR_NOEXIST);
+			tdb_close(tdb);
+		}
+	}
+
+	ok1(tap_log_messages == 0);
+	return exit_status();
+}

ccan/tdb2/test/run-21-parse_record.c

+#include <ccan/tdb2/tdb.c>
+#include <ccan/tdb2/open.c>
+#include <ccan/tdb2/free.c>
+#include <ccan/tdb2/lock.c>
+#include <ccan/tdb2/io.c>
+#include <ccan/tdb2/hash.c>
+#include <ccan/tdb2/check.c>
+#include <ccan/tdb2/transaction.c>
+#include <ccan/tap/tap.h>
+#include "logging.h"
+
+static enum TDB_ERROR parse(TDB_DATA key, TDB_DATA data, TDB_DATA *expected)
+{
+	if (data.dsize != expected->dsize)
+		return TDB_ERR_EINVAL;
+	if (memcmp(data.dptr, expected->dptr, data.dsize) != 0)
+		return TDB_ERR_EINVAL;
+	return TDB_SUCCESS;
+}
+
+static enum TDB_ERROR parse_err(TDB_DATA key, TDB_DATA data, void *unused)
+{
+	return 100;
+}
+
+static bool test_records(struct tdb_context *tdb)
+{
+	int i;
+	struct tdb_data key = { (unsigned char *)&i, sizeof(i) };
+	struct tdb_data data = { (unsigned char *)&i, sizeof(i) };
+
+	for (i = 0; i < 1000; i++) {
+		if (tdb_store(tdb, key, data, TDB_REPLACE) != 0)
+			return false;
+	}
+
+	for (i = 0; i < 1000; i++) {
+		if (tdb_parse_record(tdb, key, parse, &data) != TDB_SUCCESS)
+			return false;
+	}
+
+	if (tdb_parse_record(tdb, key, parse, &data) != TDB_ERR_NOEXIST)
+		return false;
+
+	/* Test error return from parse function. */
+	i = 0;
+	if (tdb_parse_record(tdb, key, parse_err, NULL) != 100)
+		return false;
+
+	return true;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	struct tdb_context *tdb;
+	int flags[] = { TDB_INTERNAL, TDB_DEFAULT, TDB_NOMMAP,
+			TDB_INTERNAL|TDB_CONVERT, TDB_CONVERT,
+			TDB_NOMMAP|TDB_CONVERT };
+
+	plan_tests(sizeof(flags) / sizeof(flags[0]) * 2 + 1);
+	for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+		tdb = tdb_open("run-14-exists.tdb", flags[i],
+			       O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+		if (ok1(tdb))
+			ok1(test_records(tdb));
+		tdb_close(tdb);
+	}
+
+	ok1(tap_log_messages == 0);
+	return exit_status();
+}

ccan/tdb2/traverse.c

@@ -71,3 +71,27 @@ enum TDB_ERROR tdb_nextkey(struct tdb_context *tdb, struct tdb_data *key)
 
 	return next_in_hash(tdb, &tinfo, key, NULL);
 }
+
+static int wipe_one(struct tdb_context *tdb,
+		    TDB_DATA key, TDB_DATA data, enum TDB_ERROR *ecode)
+{
+	*ecode = tdb_delete(tdb, key);
+	return (*ecode != TDB_SUCCESS);
+}
+
+enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb)
+{
+	enum TDB_ERROR ecode;
+	int64_t count;
+
+	ecode = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false);
+	if (ecode != TDB_SUCCESS)
+		return ecode;
+
+	/* FIXME: Be smarter. */
+	count = tdb_traverse(tdb, wipe_one, &ecode);
+	if (count < 0)
+		ecode = count;
+	tdb_allrecord_unlock(tdb, F_WRLCK);
+	return ecode;
+}