lmdb: update mdb_chk for checkpoints, minor cosmetics.

This is 9/9 for https://github.com/ReOpen/ReOpenLDAP/issues/1
and https://github.com/ReOpen/ReOpenLDAP/issues/2

Change-Id: I05f59313b4346c08bcd63d62e6c48a5f53c47852

lmdb.h

@@ -446,6 +446,8 @@ typedef struct MDB_envinfo {
 	size_t	me_tail_txnid;			/**< ID of the last reader transaction */
 	unsigned me_maxreaders;		/**< max reader slots in the environment */
 	unsigned me_numreaders;		/**< max reader slots used in the environment */
+	size_t me_meta1_txnid, me_meta1_sign;
+	size_t me_meta2_txnid, me_meta2_sign;
 } MDB_envinfo;
 
 	/** @brief Return the LMDB library version information.
@@ -695,7 +697,7 @@ int  mdb_env_stat(MDB_env *env, MDB_stat *stat);
 	 * @param[out] stat The address of an #MDB_envinfo structure
 	 * 	where the information will be copied
 	 */
-int  mdb_env_info(MDB_env *env, MDB_envinfo *stat);
+int  mdb_env_info(MDB_env *env, MDB_envinfo *info);
 
 	/** @brief Flush the data buffers to disk.
 	 *

mdb.c

@@ -9039,21 +9039,32 @@ mdb_env_stat(MDB_env *env, MDB_stat *arg)
 int ESECT
 mdb_env_info(MDB_env *env, MDB_envinfo *arg)
 {
-	MDB_meta *meta;
+	MDB_meta *meta, *m1, *m2;
 
 	if (env == NULL || arg == NULL)
 		return EINVAL;
 
-	meta = mdb_meta_head_r(env);
+	m1 = METAPAGE_1(env);
-	arg->me_mapaddr = meta->mm_address;
+	m2 = METAPAGE_2(env);
+
 	arg->me_mapsize = env->me_mapsize;
 	arg->me_maxreaders = env->me_maxreaders;
 	arg->me_numreaders = env->me_txns->mti_numreaders;
 
-	arg->me_last_pgno = meta->mm_last_pg;
+	do {
-	arg->me_last_txnid = meta->mm_txnid;
+		meta = mdb_meta_head_r(env);
-	arg->me_tail_txnid = 0;
+		arg->me_meta1_txnid = m1->mm_txnid;
+		arg->me_meta1_sign = m1->mm_datasync_sign;
+		arg->me_meta2_txnid = m2->mm_txnid;
+		arg->me_meta2_sign = m2->mm_datasync_sign;
+		arg->me_last_pgno = meta->mm_last_pg;
+		arg->me_last_txnid = meta->mm_txnid;
+	} while (unlikely( meta->mm_txnid != env->me_txns->mti_txnid
+			|| arg->me_meta1_sign != m1->mm_datasync_sign
+			|| arg->me_meta2_sign != m2->mm_datasync_sign ));
 
+	arg->me_mapaddr = meta->mm_address;
+	arg->me_tail_txnid = 0;
 	MDB_reader *r = env->me_txns->mti_readers;
 	int i;
 	arg->me_tail_txnid = arg->me_last_txnid;

mdb_chk.c

@@ -244,10 +244,10 @@ static long handle_freedb(size_t record_number, MDB_val *key, MDB_val* data) {
 				pg += span;
 				for (; i >= span && iptr[i - span] == pg; span++, pg++) ;
 			}
-			if (verbose > 1)
+			if (verbose > 2)
 				print(" - transaction %zu, %zd pages, maxspan %zd%s\n",
 					*(size_t *)key->mv_data, number, span, bad);
-			if (verbose > 2) {
+			if (verbose > 3) {
 				int j = number - 1;
 				while (j >= 0) {
 					pg = iptr[j];
@@ -430,6 +430,21 @@ static void usage(char *prog)
 	exit(EXIT_FAILURE);
 }
 
+const char* meta_synctype(size_t sign) {
+	switch(sign) {
+	case 0:
+		return "legacy/unknown";
+	case 1:
+		return "weak";
+	default:
+		return "steady";
+	}
+}
+
+int meta_lt(size_t txn1, size_t sign1, size_t txn2, size_t sign2) {
+	return ((sign1 > 1) == (sign2 > 1)) ? txn1 < txn2 : sign2 > 1;
+}
+
 int main(int argc, char *argv[])
 {
 	int i, rc;
@@ -437,6 +452,7 @@ int main(int argc, char *argv[])
 	char *envname;
 	int envflags = 0;
 	long problems_maindb = 0, problems_freedb = 0, problems_deep = 0;
+	int problems_meta = 0;
 	size_t n;
 
 	if (argc < 2) {
@@ -480,6 +496,8 @@ int main(int argc, char *argv[])
 	signal(SIGTERM, signal_hanlder);
 
 	envname = argv[optind];
+	print("Running mdb_chk for '%s'...\n", envname);
+
 	rc = mdb_env_create(&env);
 	if (rc) {
 		error("mdb_env_create failed, error %d %s\n", rc, mdb_strerror(rc));
@@ -523,15 +541,50 @@ int main(int argc, char *argv[])
 	}
 
 	if (verbose) {
-		print(" - map size %zu (%.1fMb, %.1fGb)\n", info.me_mapsize,
+		double k = 1024.0;
-			  (double) info.me_mapsize / (1024 * 1024),
+		const char sf[] = "KMGTPEZY"; /* LY: Kilo, Mega, Giga, Tera, Peta, Exa, Zetta, Yotta! */
-			  (double) info.me_mapsize / (1024 * 1024 * 1024));
+		for(i = 0; sf[i+1] && info.me_mapsize / k > 1000.0; ++i)
+			k *= 1024;
+		print(" - map size %zu (%.1f%cb)\n", info.me_mapsize,
+			  info.me_mapsize / k, sf[i]);
 		if (info.me_mapaddr)
 			print(" - mapaddr %p\n", info.me_mapaddr);
 		print(" - pagesize %u, max keysize %zu, max readers %u\n",
 			  stat.ms_psize, maxkeysize, info.me_maxreaders);
-		print(" - last txn %zu, tail %zu (%zi)\n", info.me_last_txnid,
+		print(" - transactions: last %zu, bottom %zu, lag reading %zi\n", info.me_last_txnid,
-			  info.me_tail_txnid, info.me_tail_txnid - info.me_last_txnid);
+			  info.me_tail_txnid, info.me_last_txnid - info.me_tail_txnid);
+
+		print(" - meta-1: %s %zu, %s",
+			   meta_synctype(info.me_meta1_sign), info.me_meta1_txnid,
+			   meta_lt(info.me_meta1_txnid, info.me_meta1_sign,
+					   info.me_meta2_txnid, info.me_meta2_sign) ? "tail" : "head");
+		print(info.me_meta1_txnid > info.me_last_txnid
+			  ? ", rolled-back %zu (%zu >>> %zu)\n" : "\n",
+			  info.me_meta1_txnid - info.me_last_txnid,
+			  info.me_meta1_txnid, info.me_last_txnid);
+
+		print(" - meta-2: %s %zu, %s",
+			   meta_synctype(info.me_meta2_sign), info.me_meta2_txnid,
+			   meta_lt(info.me_meta2_txnid, info.me_meta2_sign,
+					   info.me_meta1_txnid, info.me_meta1_sign) ? "tail" : "head");
+		print(info.me_meta2_txnid > info.me_last_txnid
+			  ? ", rolled-back %zu (%zu >>> %zu)\n" : "\n",
+			  info.me_meta2_txnid - info.me_last_txnid,
+			  info.me_meta2_txnid, info.me_last_txnid);
+	}
+
+	if (! meta_lt(info.me_meta1_txnid, info.me_meta1_sign,
+			info.me_meta2_txnid, info.me_meta2_sign)
+		&& info.me_meta1_txnid != info.me_last_txnid) {
+		print(" - meta1 txn-id mismatch\n");
+		++problems_meta;
+	}
+
+	if (! meta_lt(info.me_meta2_txnid, info.me_meta2_sign,
+			info.me_meta1_txnid, info.me_meta1_sign)
+		&& info.me_meta2_txnid != info.me_last_txnid) {
+		print(" - meta2 txn-id mismatch\n");
+		++problems_meta;
 	}
 
 	rc = mdb_txn_begin(env, NULL, MDB_RDONLY, &txn);
@@ -610,9 +663,10 @@ bailout:
 	free(pagemap);
 	if (rc)
 		return EXIT_FAILURE + 2;
-	if (problems_maindb || problems_freedb)
+	if (problems_meta || problems_maindb || problems_freedb)
 		return EXIT_FAILURE + 1;
 	if (problems_deep)
 		return EXIT_FAILURE;
+	print("No error is detected.\n");
 	return EXIT_SUCCESS;
 }