# HG changeset patch # User Adam Chlipala # Date 1445094492 14400 # Node ID 00cf8214c2e3232e01d3d750af814efc724bc57d # Parent d2a98983f502892608c3b0f6261a189139a54b6e Switching to a more dynamic method of handling database reconnection, restarting transactions diff -r d2a98983f502 -r 00cf8214c2e3 include/urweb/urweb_cpp.h --- a/include/urweb/urweb_cpp.h Sat Oct 17 10:49:25 2015 -0400 +++ b/include/urweb/urweb_cpp.h Sat Oct 17 11:08:12 2015 -0400 @@ -40,7 +40,7 @@ uw_loggers* uw_get_loggers(struct uw_context *ctx); failure_kind uw_begin(struct uw_context *, char *path); void uw_ensure_transaction(struct uw_context *); -int uw_try_reconnecting_if_at_most_one(struct uw_context *); +void uw_try_reconnecting_and_restarting(struct uw_context *); failure_kind uw_begin_onError(struct uw_context *, char *msg); void uw_login(struct uw_context *); int uw_commit(struct uw_context *); diff -r d2a98983f502 -r 00cf8214c2e3 src/c/urweb.c --- a/src/c/urweb.c Sat Oct 17 10:49:25 2015 -0400 +++ b/src/c/urweb.c Sat Oct 17 11:08:12 2015 -0400 @@ -811,12 +811,9 @@ uw_error(ctx, FATAL, "Error reopening database connection"); } -int uw_try_reconnecting_if_at_most_one(uw_context ctx) { - if (ctx->at_most_one_query) { - uw_try_reconnecting(ctx); - return 1; - } else - return 0; +void uw_try_reconnecting_and_restarting(uw_context ctx) { + uw_try_reconnecting(ctx); + uw_error(ctx, UNLIMITED_RETRY, "Restarting transaction after fixing database connection"); } void uw_ensure_transaction(uw_context ctx) { diff -r d2a98983f502 -r 00cf8214c2e3 src/mysql.sml --- a/src/mysql.sml Sat Oct 17 10:49:25 2015 -0400 +++ b/src/mysql.sml Sat Oct 17 11:08:12 2015 -0400 @@ -1,4 +1,4 @@ -(* Copyright (c) 2009-2010, Adam Chlipala +(* Copyright (c) 2009-2010, 2015, Adam Chlipala * All rights reserved. * * Redistribution and use in source and binary forms, with or without diff -r d2a98983f502 -r 00cf8214c2e3 src/postgres.sml --- a/src/postgres.sml Sat Oct 17 10:49:25 2015 -0400 +++ b/src/postgres.sml Sat Oct 17 11:08:12 2015 -0400 @@ -1,4 +1,4 @@ -(* Copyright (c) 2008-2010, 2015, Adam Chlipala +(* Copyright (c) 2008-2010, Adam Chlipala * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -520,7 +520,7 @@ newline, string "PQfinish(conn);", newline, - string "uw_error(ctx, FATAL, ", + string "uw_error(ctx, BOUNDED_RETRY, ", string "\"Connection to Postgres server failed: %s\", msg);"], newline, string "}", @@ -612,22 +612,16 @@ getter t end -fun queryCommon {loc, query, cols, doCols, runit} = +fun queryCommon {loc, query, cols, doCols} = box [string "int n, i;", newline, newline, string "if (res == NULL) {", box [newline, - string "if (uw_try_reconnecting_if_at_most_one(ctx)) {", - box [newline, - string "conn = uw_get_db(ctx);", - newline, - runit, - newline], - string "}", + string "uw_try_reconnecting_and_restarting(ctx);", newline, - string "if (res == NULL) uw_error(ctx, FATAL, \"Can't allocate query result; database server might be down.\");", + string "uw_error(ctx, FATAL, \"Can't allocate query result; database server may be down.\");", newline], string "}", newline, @@ -699,18 +693,12 @@ newline] fun query {loc, cols, doCols} = - let - val runit = string "res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);" - in - box [string "PGconn *conn = uw_get_db(ctx);", - newline, - string "PGresult *res;", - newline, - runit, - newline, - newline, - queryCommon {loc = loc, cols = cols, doCols = doCols, query = string "query", runit = runit}] - end + box [string "PGconn *conn = uw_get_db(ctx);", + newline, + string "PGresult *res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);", + newline, + newline, + queryCommon {loc = loc, cols = cols, doCols = doCols, query = string "query"}] fun p_ensql t e = case t of @@ -774,50 +762,37 @@ newline] fun queryPrepared {loc, id, query, inputs, cols, doCols, nested = _} = - let - val runit = - box [string "res = ", - if #persistent (Settings.currentProtocol ()) then - box [string "PQexecPrepared(conn, \"uw", - string (Int.toString id), - string "\", ", - string (Int.toString (length inputs)), - string ", paramValues, paramLengths, paramFormats, 0);"] - else - box [string "PQexecParams(conn, \"", - string (Prim.toCString query), - string "\", ", - string (Int.toString (length inputs)), - string ", NULL, paramValues, paramLengths, paramFormats, 0);"]] - in - box [string "PGconn *conn = uw_get_db(ctx);", - newline, - - makeParams inputs, - - newline, - string "PGresult *res;", - runit, - newline, - newline, - queryCommon {loc = loc, cols = cols, doCols = doCols, query = box [string "\"", - string (Prim.toCString query), - string "\""], - runit = runit}] - end + box [string "PGconn *conn = uw_get_db(ctx);", + newline, -fun dmlCommon {loc, dml, mode, runit} = + makeParams inputs, + + newline, + string "PGresult *res = ", + if #persistent (Settings.currentProtocol ()) then + box [string "PQexecPrepared(conn, \"uw", + string (Int.toString id), + string "\", ", + string (Int.toString (length inputs)), + string ", paramValues, paramLengths, paramFormats, 0);"] + else + box [string "PQexecParams(conn, \"", + string (Prim.toCString query), + string "\", ", + string (Int.toString (length inputs)), + string ", NULL, paramValues, paramLengths, paramFormats, 0);"], + newline, + newline, + queryCommon {loc = loc, cols = cols, doCols = doCols, query = box [string "\"", + string (Prim.toCString query), + string "\""]}] + +fun dmlCommon {loc, dml, mode} = box [string "if (res == NULL) {", box [newline, - string "if (uw_try_reconnecting_if_at_most_one(ctx)) {", - box [newline, - string "conn = uw_get_db(ctx);", - newline, - runit, - newline], - string "}", + string "uw_try_reconnecting_and_restarting(ctx);", newline, - string "if (res == NULL) uw_error(ctx, FATAL, \"Can't allocate DML result; database server might be down.\");", + string "uw_error(ctx, FATAL, \"Can't allocate DML result; database server may be down.\");", newline], string "}", newline, @@ -857,7 +832,9 @@ newline, string "if (res == NULL) {", box [newline, - string "uw_error(ctx, FATAL, \"Can't allocate DML ROLLBACK result; database server might be down.\");", + string "uw_try_reconnecting_and_restarting(ctx);", + newline, + string "uw_error(ctx, FATAL, \"Can't allocate DML ROLLBACK result; database server may be down.\");", newline], string "}", newline, @@ -892,7 +869,13 @@ newline, string "res = PQexec(conn, \"RELEASE s\");", newline, - string "if (res == NULL) uw_error(ctx, FATAL, \"Out of memory allocating DML RELEASE result.\");", + string "if (res == NULL) {", + box [newline, + string "uw_try_reconnecting_and_restarting(ctx);", + newline, + string "uw_error(ctx, FATAL, \"Can't allocate DML RELEASE result; database server may be down.\");", + newline], + string "}", newline, newline, @@ -918,7 +901,13 @@ Error => box [] | None => box [string "res = PQexec(conn, \"SAVEPOINT s\");", newline, - string "if (res == NULL) uw_error(ctx, FATAL, \"Out of memory allocating DML SAVEPOINT result.\");", + string "if (res == NULL) {", + box [newline, + string "uw_try_reconnecting_and_restarting(ctx);", + newline, + string "uw_error(ctx, FATAL, \"Can't allocate DML SAVEPOINT result; database server may be down.\");", + newline], + string "}", newline, newline, string "if (PQresultStatus(res) != PGRES_COMMAND_OK) {", @@ -934,69 +923,56 @@ newline] fun dml (loc, mode) = - let - val runit = string "res = PQexecParams(conn, dml, 0, NULL, NULL, NULL, NULL, 0);" - in - box [string "PGconn *conn = uw_get_db(ctx);", - newline, - string "PGresult *res;", - newline, + box [string "PGconn *conn = uw_get_db(ctx);", + newline, + string "PGresult *res;", + newline, - makeSavepoint mode, + makeSavepoint mode, - runit, - newline, - newline, - dmlCommon {loc = loc, dml = string "dml", mode = mode, runit = runit}] - end + string "res = PQexecParams(conn, dml, 0, NULL, NULL, NULL, NULL, 0);", + newline, + newline, + dmlCommon {loc = loc, dml = string "dml", mode = mode}] fun dmlPrepared {loc, id, dml, inputs, mode} = - let - val runit = - box [string "res = ", - if #persistent (Settings.currentProtocol ()) then - box [string "PQexecPrepared(conn, \"uw", - string (Int.toString id), - string "\", ", - string (Int.toString (length inputs)), - string ", paramValues, paramLengths, paramFormats, 0);"] - else - box [string "PQexecParams(conn, \"", - string (Prim.toCString dml), - string "\", ", - string (Int.toString (length inputs)), - string ", NULL, paramValues, paramLengths, paramFormats, 0);"]] - in - box [string "PGconn *conn = uw_get_db(ctx);", - newline, + box [string "PGconn *conn = uw_get_db(ctx);", + newline, - makeParams inputs, + makeParams inputs, - newline, - string "PGresult *res;", - newline, - newline, + newline, + string "PGresult *res;", + newline, + newline, - makeSavepoint mode, + makeSavepoint mode, - runit, - newline, - newline, - dmlCommon {loc = loc, dml = box [string "\"", - string (Prim.toCString dml), - string "\""], mode = mode, runit = runit}] - end + string "res = ", + if #persistent (Settings.currentProtocol ()) then + box [string "PQexecPrepared(conn, \"uw", + string (Int.toString id), + string "\", ", + string (Int.toString (length inputs)), + string ", paramValues, paramLengths, paramFormats, 0);"] + else + box [string "PQexecParams(conn, \"", + string (Prim.toCString dml), + string "\", ", + string (Int.toString (length inputs)), + string ", NULL, paramValues, paramLengths, paramFormats, 0);"], + newline, + newline, + dmlCommon {loc = loc, dml = box [string "\"", + string (Prim.toCString dml), + string "\""], mode = mode}] -fun nextvalCommon {loc, query, runit} = +fun nextvalCommon {loc, query} = box [string "if (res == NULL) {", box [newline, - string "if (uw_try_reconnecting_if_at_most_one(ctx))", + string "uw_try_reconnecting_and_restarting(ctx);", newline, - string "conn = uw_get_db(ctx);", - newline, - runit, - newline, - string "uw_error(ctx, FATAL, \"Out of memory allocating nextval result.\");", + string "uw_error(ctx, FATAL, \"Can't allocate NEXTVAL result; database server may be down.\");", newline], string "}", newline, @@ -1047,8 +1023,6 @@ | _ => box [string "uw_Basis_strcat(ctx, \"SELECT NEXTVAL('\", uw_Basis_strcat(ctx, ", seqE, string ", \"')\"))"] - - val runit = string "res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);" in box [string "char *query = ", query, @@ -1056,51 +1030,37 @@ newline, string "PGconn *conn = uw_get_db(ctx);", newline, - string "PGresult *res;", + string "PGresult *res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);", newline, - runit, newline, - newline, - nextvalCommon {loc = loc, query = string "query", runit = runit}] + nextvalCommon {loc = loc, query = string "query"}] end fun nextvalPrepared {loc, id, query} = - let - val runit = - box [string "res = ", - if #persistent (Settings.currentProtocol ()) then - box [string "PQexecPrepared(conn, \"uw", - string (Int.toString id), - string "\", 0, NULL, NULL, NULL, 0);"] - else - box [string "PQexecParams(conn, \"", - string (Prim.toCString query), - string "\", 0, NULL, NULL, NULL, NULL, 0);"]] - in - box [string "PGconn *conn = uw_get_db(ctx);", - newline, - newline, + box [string "PGconn *conn = uw_get_db(ctx);", + newline, + newline, + string "PGresult *res = ", + if #persistent (Settings.currentProtocol ()) then + box [string "PQexecPrepared(conn, \"uw", + string (Int.toString id), + string "\", 0, NULL, NULL, NULL, 0);"] + else + box [string "PQexecParams(conn, \"", + string (Prim.toCString query), + string "\", 0, NULL, NULL, NULL, NULL, 0);"], + newline, + newline, + nextvalCommon {loc = loc, query = box [string "\"", + string (Prim.toCString query), + string "\""]}] - string "PGresult *res;", - newline, - runit, - newline, - newline, - nextvalCommon {loc = loc, query = box [string "\"", - string (Prim.toCString query), - string "\""], runit = runit}] - end - -fun setvalCommon {loc, query, runit} = +fun setvalCommon {loc, query} = box [string "if (res == NULL) {", box [newline, - string "if (uw_try_reconnecting_if_at_most_one(ctx))", + string "uw_try_reconnecting_and_restarting(ctx);", newline, - string "conn = uw_get_db(ctx);", - newline, - runit, - newline, - string "uw_error(ctx, FATAL, \"Out of memory allocating setval result.\");", + string "uw_error(ctx, FATAL, \"Can't allocate SETVAL result; database server may be down.\");", newline], string "}", newline, @@ -1130,8 +1090,6 @@ string ", uw_Basis_strcat(ctx, \"', \", uw_Basis_strcat(ctx, uw_Basis_sqlifyInt(ctx, ", count, string "), \")\"))))"] - - val runit = string "res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);" in box [string "char *query = ", query, @@ -1139,13 +1097,10 @@ newline, string "PGconn *conn = uw_get_db(ctx);", newline, - - string "PGresult *res;", + string "PGresult *res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);", newline, - runit, newline, - newline, - setvalCommon {loc = loc, query = string "query", runit = runit}] + setvalCommon {loc = loc, query = string "query"}] end fun sqlifyString s = "E'" ^ String.translate (fn #"'" => "\\'"