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pa_sql_driver_manager.C

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/** @file
      Parser: sql driver manager implementation.

      Copyright (c) 2001-2005 ArtLebedev Group (http://www.artlebedev.com)
      Author: Alexandr Petrosian <paf@design.ru> (http://paf.design.ru)
*/

static const char * const IDENT_SQL_DRIVER_MANAGER_C="$Date: 2008-06-26 09:41:55 $";

#include "pa_sql_driver_manager.h"
#include "ltdl.h"
#include "pa_threads.h"
#include "pa_sql_connection.h"
#include "pa_exception.h"
#include "pa_common.h"
#include "pa_vhash.h"
#include "pa_vtable.h"
#include "pa_charsets.h"

// globals

00022 SQL_Driver_manager* SQL_driver_manager=0;

// consts

const time_t EXPIRE_UNUSED_CONNECTION_SECONDS=60;
const time_t CHECK_EXPIRED_CONNECTIONS_SECONDS=EXPIRE_UNUSED_CONNECTION_SECONDS*2;

// helpers

const String& SQL_Driver_services_impl::url_without_login() const {
      String& result=*new String;
      result << furl->mid(0, furl->pos(':')) << "://****";

      size_t at_pos=0;
      size_t new_at_pos;
      while( (new_at_pos=furl->pos('@', at_pos+1))!=STRING_NOT_FOUND)
            at_pos=new_at_pos;
      if(at_pos)
            result << furl->mid(at_pos, furl->length());

      return result;
}

00045 void SQL_Driver_services_impl::transcode(const char* src, size_t src_length,
      const char*& dst, size_t& dst_length,
      const char* charset_from_name,
      const char* charset_to_name
      ) 
{
      try {
            // to speed up sql transcode [lots of charsets::get-s -- twice for each cell]
            // without complicating sql driver API
            // we need to cache couple of name->charset pairs
            // assuming pointers to names are are NOT to local vars 

            struct cache_record {
                  const char* name;
                  Charset* object;
            } cache[2]={{0,0}, {0,0}};

            Charset* charset_from_object;
            Charset* charset_to_object;
            if(charset_from_name==cache[0].name) {
                  charset_from_object=cache[0].object;
            } else {
                  cache[0].name=charset_from_name;
                  cache[0].object=charset_from_object=&charsets.get(charset_from_name);
            }
            if(charset_to_name==cache[1].name) {
                  charset_to_object=cache[1].object;
            } else {
                  cache[1].name=charset_to_name;
                  cache[1].object=charset_to_object=&charsets.get(charset_to_name);
            }

            String::C result=Charset::transcode(String::C(src, src_length), 
                  *charset_from_object,
                  *charset_to_object);
            dst=result.str;
            dst_length=result.length;
      } catch(const Exception& e) {
            _throw(SQL_Error(e.type(), e.comment()));
      } catch(...) {
            _throw(SQL_Error(0, "unknown error while transcoding in sql driver"));
      }
}

// helpers

static void expire_connection(SQL_Connection& connection, time_t older_dies) {
      if(connection.connected() && connection.expired(older_dies))
            connection.disconnect();
}
static void expire_connections(SQL_Driver_manager::connection_cache_type::key_type /*key*/, 
                         SQL_Driver_manager::connection_cache_type::value_type stack, 
                         time_t older_dies) {
      for(size_t i=0; i<stack->top_index(); i++)
            expire_connection(*stack->get(i), older_dies);
}

// SQL_Driver_manager

SQL_Driver_manager::SQL_Driver_manager(): 
      is_dlinited(false), prev_expiration_pass_time(0) {
}

SQL_Driver_manager::~SQL_Driver_manager() {
      connection_cache.for_each<time_t>(expire_connections, time(0)+(time_t)10/*=in future=expire all*/);

      if(is_dlinited)
            lt_dlexit();
}

/// @param aurl protocol://[driver-dependent]
00116 SQL_Connection* SQL_Driver_manager::get_connection(const String& aurl,
                                       Table *protocol2driver_and_client,
                                       const char* arequest_charset,
                                       const char* adocument_root) {
      // we have table for locating protocol's library
      if(!protocol2driver_and_client)
            throw Exception(PARSER_RUNTIME,
                  &aurl,
                  "$"MAIN_SQL_NAME":"MAIN_SQL_DRIVERS_NAME" table must be defined");

      // first trying to get cached connection
      SQL_Connection* connection=get_connection_from_cache(aurl);
      if(connection) {
            connection->set_url();
            if(!connection->ping()) { // we have some cached connection, is it pingable?
                  connection->disconnect(); // kill unpingabe=dead connection
                  connection=0;
            }
      }

      char *url_cstr;
      if(connection)
            url_cstr=0; // calm, compiler
      else { // no cached connection or it were unpingabe: connect/reconnect
            url_cstr=aurl.cstrm();
            if(!strstr(url_cstr, "://"))
                  throw Exception(PARSER_RUNTIME,
                        aurl.length()?&aurl:0,
                        "connection string must start with protocol://");


            char *protocol_cstr=lsplit(&url_cstr, ':');
            // skip "//" after ':'
            while(*url_cstr=='/')
                  url_cstr++;
            const String& protocol=*new String(protocol_cstr);

            SQL_Driver *driver;
            // first trying to get cached driver
            if(!(driver=get_driver_from_cache(protocol))) {
                  // no cached
                  const String* library=0;
                  const String* dlopen_file_spec=0;
                  Table::Action_options options;
                  if(protocol2driver_and_client->locate(0, protocol, options)) {
                        if(!(library=protocol2driver_and_client->item(1)) || library->length()==0)
                              throw Exception(PARSER_RUNTIME,
                                    0,
                                    "driver library column for protocol '%s' is empty", 
                                          protocol_cstr);
                        dlopen_file_spec=protocol2driver_and_client->item(2);
                  } else
                        throw Exception(PARSER_RUNTIME,
                              &aurl,
                              "undefined protocol '%s'", 
                                    protocol_cstr);

                  if(!is_dlinited) {
                        if(lt_dlinit())
                              throw Exception(0,
                                    library,
                                    "prepare to dynamic loading failed, %s", lt_dlerror());

                        is_dlinited=true;
                  }

                  const char* filename=library->cstr(String::L_FILE_SPEC);
                  lt_dlhandle handle=lt_dlopen(filename);
                  if (!handle) {
                        const char* error=lt_dlerror();
                        throw Exception(0,
                              library,
                              error?error:"can not open the module");
                  }

                  SQL_Driver_create_func create=(SQL_Driver_create_func)(lt_dlsym(handle, 
                        SQL_DRIVER_CREATE_NAME));
                  if(!create)
                        throw Exception(0,
                              library,
                              "function '"SQL_DRIVER_CREATE_NAME"' was not found");

                  // create library-driver!
                  driver=(*create)();

                  // validate driver api version
                  int driver_api_version=driver->api_version();
                  if(driver_api_version!=SQL_DRIVER_API_VERSION)
                        throw Exception(0,
                              library,
                              "driver implements API version 0x%04X not equal to 0x%04X",
                                    driver_api_version, SQL_DRIVER_API_VERSION);

                  // initialise by connecting to sql client dynamic link library
                  char* dlopen_file_spec_cstr=
                        dlopen_file_spec && dlopen_file_spec->length()?
                        dlopen_file_spec->cstrm(String::L_AS_IS):0;
                  if(const char* error=driver->initialize(dlopen_file_spec_cstr))
                        throw Exception(0,
                              library,
                              "driver failed to initialize client library '%s', %s",
                                    dlopen_file_spec_cstr?dlopen_file_spec_cstr:"unspecifed",
                                    error);

                  // cache it
                  put_driver_to_cache(protocol, driver);
            }
      
            connection=new SQL_Connection(aurl, *driver, arequest_charset, adocument_root);
            // associate with pool[request]  (deassociates at close)
            connection->set_url(); 
      }

      // if not connected yet, do that now, when connection has services
      if(!connection->connected())
            connection->connect(url_cstr);
      // return autoclosing object for it
      return connection;
}

00236 void SQL_Driver_manager::close_connection(connection_cache_type::key_type url, 
                                SQL_Connection* connection) {
      put_connection_to_cache(url, connection);
}


// driver cache

SQL_Driver *SQL_Driver_manager::get_driver_from_cache(driver_cache_type::key_type protocol) {
      SYNCHRONIZED;

      return driver_cache.get(protocol);
}

void SQL_Driver_manager::put_driver_to_cache(
                                                                   driver_cache_type::key_type protocol, 
                                                                   driver_cache_type::value_type driver) {
      SYNCHRONIZED;

      driver_cache.put(protocol, driver);
}

// connection cache
/// @todo get rid of memory spending Stack [zeros deep inside got accumulated]
00260 SQL_Connection* SQL_Driver_manager::get_connection_from_cache(connection_cache_type::key_type url) { 
      SYNCHRONIZED;

      if(connection_cache_type::value_type connections=connection_cache.get(url))
            while(!connections->is_empty()) { // there are cached connections to that 'url'
                  SQL_Connection* result=connections->pop();
                  if(result->connected()) // not expired?
                        return result;
            }

      return 0;
}

void SQL_Driver_manager::put_connection_to_cache(
                                     connection_cache_type::key_type url, 
                                     SQL_Connection* connection) { 
      SYNCHRONIZED;

      connection_cache_type::value_type connections=connection_cache.get(url);
      if(!connections) { // there are no cached connections to that 'url' yet?
            connections=new connection_cache_element_base_type;
            connection_cache.put(url, connections);
      }     
      connections->push(connection);
}

void SQL_Driver_manager::maybe_expire_cache() {
      time_t now=time(0);

      if(prev_expiration_pass_time<now-CHECK_EXPIRED_CONNECTIONS_SECONDS) {
            connection_cache.for_each<time_t>(expire_connections, time_t(now-EXPIRE_UNUSED_CONNECTION_SECONDS));

            prev_expiration_pass_time=now;
      }
}

static void add_connection_to_status_cache_table(SQL_Connection& connection, Table* table) {
      if(connection.connected()) {
            ArrayString& row=*new ArrayString;

            // url
            row+=&connection.services().url_without_login();
            // time
            time_t time_used=connection.get_time_used();
            row+=new String(pa_strdup(ctime(&time_used)));

            *table+=&row;
      }
}
static void add_connections_to_status_cache_table(
      SQL_Driver_manager::connection_cache_type::key_type /*key*/, 
      SQL_Driver_manager::connection_cache_type::value_type stack, Table* table) 
{
      for(Array_iterator<SQL_Connection*> i(*stack); i.has_next(); )
            add_connection_to_status_cache_table(*i.next(), table);
}

00317 Value* SQL_Driver_manager::get_status() {
      Value* result=new VHash;

      // cache
      {
            ArrayString& columns=*new ArrayString;
            columns+=new String("url");
            columns+=new String("time");
            Table& table=*new Table(&columns, connection_cache.count());

            connection_cache.for_each<Table*>(add_connections_to_status_cache_table, &table);

            result->get_hash()->put(*new String("cache"), new VTable(&table));
      }

      return result;
}

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