exmdb: rework get_mbox_perm queries (1/2)

get_mbox_perm performs not great in the face of many ACEs:

* SELECT … LEFT JOIN … LEFT JOIN: 62096 µs
* mlist membership test: 3586543 µs
* [5950X system with 100k ACEs]

Rewrite the LEFT JOIN as two separate queries.
The sections now complete in

* SELECTs: 1432 µs
* mlist: 360306 µs

References: DESK-3893, DESK-3984

Author: jengelh

exch/exmdb/store.cpp

@@ -12,6 +12,7 @@
 #include <gromox/database.h>
 #include <gromox/exmdb_common_util.hpp>
 #include <gromox/exmdb_server.hpp>
+#include <gromox/flat_set.hpp>
 #include <gromox/list_file.hpp>
 #include <gromox/mapidefs.h>
 #include <gromox/mysql_adaptor.hpp>
@@ -231,18 +232,16 @@ BOOL exmdb_server::get_mbox_perm(const char *dir,
 	*ppermission = rightsNone;
 
 	/* Store permission := union of folder permissions */
+	gromox::maybe_flat_set<uint64_t> seen_fid;
 	auto pstmt = gx_sql_prep(pdb->psqlite,
-	             "SELECT p1.folder_id, p2.permission, p3.permission "
-	             "FROM permissions AS p1 LEFT JOIN permissions AS p2 "
-	             "ON p1.folder_id=p2.folder_id AND p2.username=? "
-	             "LEFT JOIN permissions AS p3 "
-	             "ON p1.folder_id=p3.folder_id AND p3.username='default'");
+	             "SELECT folder_id, permission FROM permissions WHERE username=?");
 	if (pstmt == nullptr)
 		return FALSE;
 	sqlite3_bind_text(pstmt, 1, username, -1, SQLITE_STATIC);
 	while (pstmt.step() == SQLITE_ROW) {
 		auto fid  = pstmt.col_uint64(0);
-		auto perm = pstmt.col_uint64(sqlite3_column_type(pstmt, 1) != SQLITE_NULL ? 1 : 2);
+		auto perm = pstmt.col_uint64(1);
+		seen_fid.emplace(fid);
 		*ppermission |= perm;
 	/*
 	 * Outlook and g-web only expose IPM_SUBTREE and below, so permissions
@@ -262,6 +261,17 @@ BOOL exmdb_server::get_mbox_perm(const char *dir,
 		if (fid == PRIVATE_FID_IPMSUBTREE && perm & frightsOwner)
 			*ppermission |= frightsGromoxStoreOwner;
 	}
+	pstmt.reset();
+	pstmt.bind_text(1, "default");
+	while (pstmt.step() == SQLITE_ROW) {
+		auto fid = pstmt.col_uint64(0);
+		if (seen_fid.find(fid) != seen_fid.end())
+			continue;
+		auto perm = pstmt.col_uint64(1);
+		*ppermission |= perm;
+		if (fid == PRIVATE_FID_IPMSUBTREE && perm & frightsOwner)
+			*ppermission |= frightsGromoxStoreOwner;
+	}
 	pstmt.finalize();
 
 	/* add in mlist permissions(?) */

lib/dbop_sqlite.cpp

@@ -113,6 +113,17 @@ static constexpr char tbl_perms_0[] =
 "CREATE INDEX fid_permissions_index ON permissions(folder_id);"
 "CREATE UNIQUE INDEX folder_username_index ON permissions(folder_id, username);";
 
+static constexpr char tbl_perms_24[] =
+"CREATE TABLE permissions ("
+"  member_id INTEGER PRIMARY KEY AUTOINCREMENT,"
+"  folder_id INTEGER NOT NULL,"
+"  username TEXT COLLATE NOCASE NOT NULL,"
+"  permission INTEGER NOT NULL,"
+"  FOREIGN KEY (folder_id) REFERENCES folders (folder_id) ON DELETE CASCADE ON UPDATE CASCADE);"
+"CREATE INDEX fid_permissions_index ON permissions(folder_id);"
+"CREATE UNIQUE INDEX folder_username_index ON permissions(folder_id, username);"
+"CREATE UNIQUE INDEX folder_username_index2 ON permissions(username, folder_id);";
+
 static constexpr char tbl_rules_0[] =
 "CREATE TABLE rules ("
 "  rule_id INTEGER PRIMARY KEY AUTOINCREMENT,"
@@ -372,6 +383,9 @@ tbl_addmsgtimeindex_23[] =
 "LEFT JOIN message_properties AS rt ON m.message_id=rt.message_id AND rt.proptag=0xe060040 " /* PR_MESSAGE_DELIVERY_TIME */
 "LEFT JOIN message_properties AS st ON m.message_id=st.message_id AND st.proptag=0x390040 " /* PR_CLIENT_SUBMIT_TIME */
 "WHERE m.parent_fid IS NOT NULL AND m.is_associated=0 AND m.is_deleted=0";
+static constexpr char tbl_mboxpermissionindex_24[] =
+/* this helps determining mbox perm (bitwise-OR of all folders) */
+"CREATE UNIQUE INDEX folder_username_index2 ON permissions(username, folder_id);";
 
 static constexpr char tbl_pub_folders_0[] =
 "CREATE TABLE folders ("
@@ -451,7 +465,7 @@ static constexpr tbl_init tbl_pvt_init_top[] = {
 	{"named_properties", tbl_namedprops_12},
 	{"store_properties", tbl_storeprops_2},
 	{"folder_properties", tbl_fldprops_3},
-	{"permissions", tbl_perms_0},
+	{"permissions", tbl_perms_24},
 	{"rules", tbl_rules_0},
 	{"message_properties", tbl_msgprops_4},
 	{"message_changes", tbl_msgchgs_0},
@@ -498,7 +512,7 @@ static constexpr tbl_init tbl_pub_init_top[] = {
 	{"named_properties", tbl_namedprops_0},
 	{"store_properties", tbl_storeprops_2},
 	{"folder_properties", tbl_fldprops_3},
-	{"permissions", tbl_perms_0},
+	{"permissions", tbl_perms_24},
 	{"rules", tbl_rules_0},
 	{"message_properties", tbl_msgprops_4},
 	{"message_changes", tbl_msgchgs_0},
@@ -640,6 +654,7 @@ static constexpr tblite_upgradefn tbl_pvt_upgrade_list[] = {
 	{21, tbl_mtimeindex_21},
 	{22, tbl_msgtimeindex_22},
 	{23, tbl_addmsgtimeindex_23},
+	{24, tbl_mboxpermissionindex_24},
 	/* advance schema numbers in lockstep with public stores */
 	TABLE_END,
 };
@@ -660,6 +675,7 @@ static constexpr tblite_upgradefn tbl_pub_upgrade_list[] = {
 	{21, tbl_mtimeindex_21},
 	{22, tbl_msgtimeindex_22},
 	{23, tbl_addmsgtimeindex_23},
+	{24, tbl_mboxpermissionindex_24},
 	/* advance schema numbers in lockstep with private stores */
 	TABLE_END,
 };