--- parser3/src/classes/op.C 2001/12/19 16:17:26 1.65 +++ parser3/src/classes/op.C 2002/03/04 10:03:35 1.72 @@ -1,10 +1,10 @@ /** @file Parser: parser @b operators. - Copyright (c) 2001 ArtLebedev Group (http://www.artlebedev.com) - Author: Alexander Petrosyan (http://paf.design.ru) + Copyright (c) 2001, 2002 ArtLebedev Group (http://www.artlebedev.com) + Author: Alexandr Petrosian (http://paf.design.ru) - $Id: op.C,v 1.65 2001/12/19 16:17:26 paf Exp $ + $Id: op.C,v 1.72 2002/03/04 10:03:35 paf Exp $ */ #include "classes.h" @@ -124,7 +124,10 @@ static void _process(Request& r, const S // process source code, append processed methods to 'self' class // maybe-define new @main - r.use_buf(source.cstr(String::UL_UNSPECIFIED, r.connection), place, &self_class); + r.use_buf( + source.cstr(String::UL_UNSPECIFIED, r.connection(0)), + place, + &self_class); // maybe-execute @main[] if(const Method *method=self_class.get_method(*main_method_name)) { @@ -245,7 +248,7 @@ struct timeval mt[2]; gettimeofday(&mt[0],NULL); #endif // connect - SQL_Connection& connection=SQL_driver_manager->get_connection( + SQL_Connection_ptr connection=SQL_driver_manager->get_connection( url.as_string(), method_name, protocol2driver_and_client); #ifdef RESOURCES_DEBUG @@ -258,35 +261,15 @@ for(int i=0;i<2;i++) r.sql_connect_time+=t[1]-t[0]; #endif - // remember/set current connection - SQL_Connection *saved_connection=r.connection; - r.connection=&connection; + Temp_connection temp_connection(r, connection.get()); // execute body try { - try { - r.write_assign_lang(r.process(body_code)); - - connection.commit(); - } catch(...) { // process/commit problem - connection.rollback(); - - /*re*/throw; - } - - } catch(...) { - // close connection [cache it] - connection.close(); - // recall current connection from remembered - r.connection=saved_connection; - - /*re*/throw; + r.write_assign_lang(r.process(body_code)); + + } catch(...) { // process/commit problem + connection->mark_to_rollback(); + /*re*/throw; } - - // and anyway - // close connection [cache it] - connection.close(); - // recall current connection from remembered - r.connection=saved_connection; } #ifndef DOXYGEN @@ -355,54 +338,75 @@ struct Data_string_serialized_prolog { }; #endif -void cache_delete(Pool& pool, const String& file_spec) { - file_delete(pool, file_spec, false/*fail_on_read_problem*/); +void cache_delete(const String& file_spec) { + file_delete(file_spec, false/*fail_on_read_problem*/); } -void cache_put(Pool& pool, const String& file_spec, const String& data_string) { + +#ifndef DOXYGEN +struct Locked_process_and_cache_put_action_info { + Request *r; + Value *body; +}; +#endif +static void locked_process_and_cache_put_action(int f, void *context) { + Locked_process_and_cache_put_action_info& info= + *static_cast(context); + + // body->process + info.body=&info.r->process(*info.body); + + // result->string + const String& data_string=info.body->as_string(); + + // string -serialize> buffer void *data; size_t data_size; data_string.serialize( sizeof(Data_string_serialized_prolog), data, data_size); Data_string_serialized_prolog& prolog= *static_cast(data); - prolog.version=DATA_STRING_SERIALIZED_VERSION; - - file_write(pool, - file_spec, - data, data_size, - false/*as_text*/); + + // buffer -write> file + write(f, data, data_size); +} +Value *locked_process_and_cache_put(Request& r, + Value& body_code, + const String& file_spec) { + Locked_process_and_cache_put_action_info info={ + &r, + &body_code, + }; + + return file_write_action_under_lock( + file_spec, + "cache_put", locked_process_and_cache_put_action, &info, + false/*as_text*/, + false/*do_append*/, + false/*block*/) ? info.body : 0; } String *cache_get(Pool& pool, const String& file_spec) { void* data; size_t data_size; - if(!file_read(pool, file_spec, + if(file_read(pool, file_spec, data, data_size, false/*as_text*/, - false/*fail_on_read_problem*/)) - return 0; + false/*fail_on_read_problem*/) + && data_size/* ignore reads which are empty due to + non-unary open+lockEX conflict with lockSH */) { - Data_string_serialized_prolog& prolog= - *static_cast(data); - - if(data_size(data); - if(prolog.version!=DATA_STRING_SERIALIZED_VERSION) - throw Exception(0, 0, - &file_spec, - "data string version 0x%04X not equal to 0x%04X, recreate file", - prolog.version, DATA_STRING_SERIALIZED_VERSION); - - String& result=*new(pool) String(pool); - if(data_size) { - result.deserialize( - sizeof(Data_string_serialized_prolog), - data, data_size, file_spec.cstr()); + String *result=new(pool) String(pool); + if( + data_size>=sizeof(Data_string_serialized_prolog) + && prolog.version==DATA_STRING_SERIALIZED_VERSION + && result->deserialize( + sizeof(Data_string_serialized_prolog), data, data_size, file_spec.cstr())) + return result; } - - return &result; + + return 0; } static void _cache(Request& r, const String& method_name, MethodParams *params) { Pool& pool=r.pool(); @@ -410,7 +414,7 @@ static void _cache(Request& r, const Str // file_spec, expires, body code const String &file_spec=r.absolute(params->as_string(0, "filespec must be string")); if(params->size()==1) { // delete - cache_delete(pool, file_spec); + cache_delete(file_spec); return; } @@ -420,29 +424,61 @@ static void _cache(Request& r, const Str if(lifespan) { // 'lifespan' specified? try cached copy... size_t size; time_t atime, mtime, ctime; + + // hence we don't hope to have unary create/lockEX + // we need some plan to live in a life like that, so... + // worst races plan: + // A B + // open + // |open + // lockSH + // |nonblocking-lockEX fails + // unlockSH + // close, cache_get returns 0 + // open + // nonblocking-lockEX succeeds; process, write, close + // |retry1: open + // ... + // |lockSH succeeds; ... + // {file_spec} modification time - if(!file_stat(file_spec, size, atime, mtime, ctime, false/*no exception on error*/) - || (time(0)-mtime) > lifespan) // cached file expired - cache_delete(pool, file_spec); - else - if(String *cached_body=cache_get(pool, file_spec)) { // have cached copy? + for(int retry=0; retry<2; retry++) { + if(file_stat(file_spec, size, atime, mtime, ctime, false/*no exception on error*/)) // exists? + if(time(0)-mtime > lifespan) // expired + cache_delete(file_spec); + else // not expired + if(String *cached_body=cache_get(pool, file_spec)) { // have cached copy? + // write it out + r.write_assign_lang(*cached_body); + // happy with it + return; + } + + // non-blocked lock; process; cache it + if(Value *processed_body=locked_process_and_cache_put(r, body_code, file_spec)) { // write it out - r.write_assign_lang(*cached_body); + r.write_assign_lang(*processed_body); // happy with it return; + } else { // somebody writing result right now + pa_sleep(0, 500000); // waiting half a second + retry=0; // prolonging our wait, than could cache_get it, without processing body_code } - } else // 'lifespan'=0, forget cached copy - cache_delete(pool, file_spec); - - // process - Value& processed_body=r.process(body_code); - - // put it to cache if 'lifespan' specified - if(lifespan) - cache_put(pool, file_spec, processed_body.as_string()); - - // write it out - r.write_assign_lang(processed_body); + } + throw Exception(0, 0, + &file_spec, + "locking problem"); + } else { + // 'lifespan'=0, forget cached copy + cache_delete(file_spec); + // process + Value& processed_body=r.process(body_code); + // write it out + r.write_assign_lang(processed_body); + // happy with it + return; + } + // never reached } // constructor