terminate a canceled session when its last connection is closed. (#520)

internal/db/migrations/postgres.gen.go

@@ -4010,7 +4010,7 @@ begin;
   after insert on session_connection
     for each row execute procedure insert_new_connection_state();
 
-  -- update_connection_state_on_closed_reason() is used in an update insert trigger on the
+  -- update_connection_state_on_closed_reason() is used in an update trigger on the
   -- session_connection table.  it will insert a state of "closed" in
   -- session_connection_state for the closed session connection. 
   create or replace function 
@@ -4031,6 +4031,9 @@ begin;
         values
           (new.public_id, 'closed');
       end if;
+      -- whenever we close a connection, we want to terminate the session if
+      -- possible.  
+      perform terminate_session_if_possible(new.session_id);
     end if;
     return new;
   end;
@@ -4116,6 +4119,94 @@ begin;
   create trigger insert_session_connection_state before insert on session_connection_state
     for each row execute procedure insert_session_connection_state();
 
+-- terminate_session_if_possible takes a session id and terminates the session
+-- if the following conditions are met:
+--    * the session is expired and all its connections are closed.
+--    * the session is canceling and all its connections are closed
+--    * the session has exhausted its connection limit and all its connections
+--      are closed.  
+--
+--      Note: this function should align closely with the domain function
+--      TerminateCompletedSessions 
+create or replace function 
+    terminate_session_if_possible(terminate_session_id text)
+    returns void
+  as $$
+  begin 
+    -- is terminate_session_id in a canceling state
+    with canceling_session(session_id) as
+    (
+      select 
+        session_id
+      from
+        session_state ss
+      where 
+        ss.session_id = terminate_session_id and
+        ss.state = 'canceling' and 
+        ss.end_time is null
+    )
+    update session us
+      set termination_reason = 
+      case 
+        -- timed out sessions
+        when now() > us.expiration_time then 'timed out'
+        -- canceling sessions
+        when us.public_id in(
+          select 
+            session_id 
+          from 
+            canceling_session cs 
+          where
+            us.public_id = cs.session_id
+          ) then 'canceled' 
+        -- default: session connection limit reached.
+        else 'connection limit'
+      end
+    where
+      -- limit update to just the terminating_session_id
+      us.public_id = terminate_session_id and
+      termination_reason is null and
+      -- session expired or connection limit reached
+      (
+        -- expired sessions...
+        now() > us.expiration_time or 
+        -- connection limit reached...
+        (
+          select count (*) 
+            from session_connection sc 
+          where 
+            sc.session_id = us.public_id
+        ) >= connection_limit or 
+        -- canceled sessions
+        us.public_id in (
+          select 
+            session_id
+          from
+            canceling_session cs
+          where 
+            us.public_id = cs.session_id 
+        )
+      ) and 
+      -- make sure there are no existing connections
+      us.public_id not in (
+        select 
+          session_id 
+        from 
+            session_connection
+          where public_id in (
+          select 
+            connection_id
+          from 
+            session_connection_state
+          where 
+            state != 'closed' and
+            end_time is null
+        )
+    );
+ end;
+  $$ language plpgsql;
+
+
 commit;
 
 `),

internal/db/migrations/postgres/51_connection.up.sql

@@ -174,7 +174,7 @@ begin;
   after insert on session_connection
     for each row execute procedure insert_new_connection_state();
 
-  -- update_connection_state_on_closed_reason() is used in an update insert trigger on the
+  -- update_connection_state_on_closed_reason() is used in an update trigger on the
   -- session_connection table.  it will insert a state of "closed" in
   -- session_connection_state for the closed session connection. 
   create or replace function 
@@ -195,6 +195,9 @@ begin;
         values
           (new.public_id, 'closed');
       end if;
+      -- whenever we close a connection, we want to terminate the session if
+      -- possible.  
+      perform terminate_session_if_possible(new.session_id);
     end if;
     return new;
   end;
@@ -280,4 +283,92 @@ begin;
   create trigger insert_session_connection_state before insert on session_connection_state
     for each row execute procedure insert_session_connection_state();
 
+-- terminate_session_if_possible takes a session id and terminates the session
+-- if the following conditions are met:
+--    * the session is expired and all its connections are closed.
+--    * the session is canceling and all its connections are closed
+--    * the session has exhausted its connection limit and all its connections
+--      are closed.  
+--
+--      Note: this function should align closely with the domain function
+--      TerminateCompletedSessions 
+create or replace function 
+    terminate_session_if_possible(terminate_session_id text)
+    returns void
+  as $$
+  begin 
+    -- is terminate_session_id in a canceling state
+    with canceling_session(session_id) as
+    (
+      select 
+        session_id
+      from
+        session_state ss
+      where 
+        ss.session_id = terminate_session_id and
+        ss.state = 'canceling' and 
+        ss.end_time is null
+    )
+    update session us
+      set termination_reason = 
+      case 
+        -- timed out sessions
+        when now() > us.expiration_time then 'timed out'
+        -- canceling sessions
+        when us.public_id in(
+          select 
+            session_id 
+          from 
+            canceling_session cs 
+          where
+            us.public_id = cs.session_id
+          ) then 'canceled' 
+        -- default: session connection limit reached.
+        else 'connection limit'
+      end
+    where
+      -- limit update to just the terminating_session_id
+      us.public_id = terminate_session_id and
+      termination_reason is null and
+      -- session expired or connection limit reached
+      (
+        -- expired sessions...
+        now() > us.expiration_time or 
+        -- connection limit reached...
+        (
+          select count (*) 
+            from session_connection sc 
+          where 
+            sc.session_id = us.public_id
+        ) >= connection_limit or 
+        -- canceled sessions
+        us.public_id in (
+          select 
+            session_id
+          from
+            canceling_session cs
+          where 
+            us.public_id = cs.session_id 
+        )
+      ) and 
+      -- make sure there are no existing connections
+      us.public_id not in (
+        select 
+          session_id 
+        from 
+            session_connection
+          where public_id in (
+          select 
+            connection_id
+          from 
+            session_connection_state
+          where 
+            state != 'closed' and
+            end_time is null
+        )
+    );
+ end;
+  $$ language plpgsql;
+
+
 commit;

internal/session/repository_session_test.go

@@ -892,13 +892,16 @@ func TestRepository_TerminateCompletedSessions(t *testing.T) {
 				return
 			}
 			assert.NoError(err)
-			assert.Equal(len(args.wantTermed), got)
-
+			t.Logf("terminated: %d", got)
+			var foundTerminated int
 			for _, ses := range args.sessions {
 				found, _, err := repo.LookupSession(context.Background(), ses.PublicId)
 				require.NoError(err)
 				_, shouldBeTerminated := args.wantTermed[found.PublicId]
 				if shouldBeTerminated {
+					if found.TerminationReason != "" {
+						foundTerminated += 1
+					}
 					assert.Equal(args.wantTermed[found.PublicId].String(), found.TerminationReason)
 					t.Logf("terminated %s has a connection limit of %d", found.PublicId, found.ConnectionLimit)
 					conn, err := repo.ListConnections(context.Background(), found.PublicId)
@@ -925,7 +928,7 @@ func TestRepository_TerminateCompletedSessions(t *testing.T) {
 					}
 				}
 			}
-
+			assert.Equal(len(args.wantTermed), foundTerminated)
 		})
 	}
 }