PostRR_update(): Use rrtimeslice_cmp() to decide how to do the update.

[postrr.git] / src / postrr.sql.in

diff --git a/src/postrr.sql.in b/src/postrr.sql.in
index 87ef9d36a3cabbe40450ef19c686b9e3bec5d126..9f34f22100cfd04151da1afb56ca23ec2c3538d8 100644 (file)
--- a/src/postrr.sql.in
+++ b/src/postrr.sql.in
@@ -320,6 +320,7 @@ DECLARE
        ts_str text;
        v_str text;
        update_qry text;
+       status integer;
        newts rrtimeslice;
        new cdata;
 BEGIN
@@ -330,13 +331,13 @@ BEGIN
 
        update_qry = 'CData_update(' || vcol || ', ' || v_str || ')';
 
+       -- XXX: handle race conditions
+
        BEGIN
-               EXECUTE 'UPDATE ' || tbl
-                       || ' SET ' || tscol || ' = ' || ts_str
-                       || ', ' || vcol || ' = ' || update_qry
+               EXECUTE 'SELECT rrtimeslice_cmp(' || tscol || ', ' || ts_str
+                       || ') AS status FROM ' || tbl
                        || ' WHERE ' || tscol || ' = ' || ts_str
-                       || ' RETURNING ' || tscol || ', ' || vcol
-                       INTO STRICT newts, new;
+                       INTO STRICT status;
 
                EXCEPTION
                        WHEN NO_DATA_FOUND THEN
@@ -346,9 +347,29 @@ BEGIN
                                        || ') RETURNING ' || tscol || ', ' || vcol
                                        INTO newts, new;
                                -- use strict again; on exception retry?
+                               RETURN new;
                        WHEN TOO_MANY_ROWS THEN
                                RAISE EXCEPTION '% is not unique in %.%', ts_str, tbl, tscol;
        END;
+
+       IF status = 0 THEN
+               -- timestamps match
+               EXECUTE 'UPDATE ' || tbl
+                       || ' SET ' || vcol || ' = ' || update_qry
+                       || ' WHERE ' || tscol || ' = ' || ts_str
+                       || ' RETURNING ' || tscol || ', ' || vcol
+                       INTO STRICT newts, new;
+       ELSIF status < 0 THEN
+               -- given timestamp is newer than in the database
+               EXECUTE 'UPDATE ' || tbl
+                       || ' SET ' || tscol || ' = ' || ts_str
+                       || ', ' || vcol || ' = ' || v_str
+                       || ' WHERE ' || tscol || ' = ' || ts_str
+                       || ' RETURNING ' || tscol || ', ' || vcol
+                       INTO STRICT newts, new;
+       ELSE
+               RAISE EXCEPTION '% is too old in %.%', ts_str, tbl, tscol;
+       END IF;
        RETURN new;
 END;
 $$;