java - JPA, Hibernate with c3p0 and Postgres. Detect database connectivity issues -

i'm writing application connects postgres db via hibernate c3p0 pooling. before main interface shows i'd detect whatever database connectivity settings valid , connection db possible. if settings not valid i'd show message user , suggest change settings or close application. problem entitymanagerfactory won't throw exception or return after unsuccessful connection.

here example of code produces error wrong connection settings:

public void connect(connectionsettingsmodel conset) throws exception {     map<string, string> connectionproperties = new hashmap<>();     connectionproperties.put("javax.persistence.jdbc.url", conset.geturl());     connectionproperties.put("javax.persistence.jdbc.user", conset.getuser());     connectionproperties.put("javax.persistence.jdbc.password", conset.getpassword());     connectionproperties.put("hibernate.default_schema", conset.getschema());      system.out.println("before creating em");     entitymanagerfactory entitymanagerfactory = persistence.createentitymanagerfactory("postgres-connect", connectionproperties);     entitymanager entitymanager = entitymanagerfactory.createentitymanager();     system.out.println("after creating em");  } 

c3p0 configuration in persistence.xml:

<property name="hibernate.connection.provider_class" value="org.hibernate.connection.c3p0connectionprovider"/> <property name="hibernate.c3p0.min_size" value="0"/> <property name="hibernate.c3p0.max_size" value="10"/> <property name="hibernate.c3p0.timeout" value="300"/> <property name="hibernate.c3p0.idle_test_period" value="3000"/> <property name="hibernate.c3p0.max_statements" value="50"/> <property name="hibernate.c3p0.acquireretryattempts" value="1"/> 

an log example non existent user name:

before creating em 14:47:07,009 info [com.mchange.v2.log.mlog] - mlog clients using log4j logging. 14:47:07,239 info [com.mchange.v2.c3p0.c3p0registry] - initializing c3p0-0.9.5.2 [built 08-december-2015 22:06:04 -0800; debug? true; trace: 10] 14:47:07,303 info [com.mchange.v2.c3p0.impl.abstractpoolbackeddatasource] - initializing c3p0 pool... com.mchange.v2.c3p0.poolbackeddatasource@e945fe41 [ connectionpooldatasource -> com.mchange.v2.c3p0.wrapperconnectionpooldatasource@d1b84bda [ acquireincrement -> 3, acquireretryattempts -> 1, acquireretrydelay -> 1000, autocommitonclose -> false, automatictesttable -> null, breakafteracquirefailure -> false, checkouttimeout -> 0, connectioncustomizerclassname -> null, connectiontesterclassname -> com.mchange.v2.c3p0.impl.defaultconnectiontester, contextclassloadersource -> caller, debugunreturnedconnectionstacktraces -> false, factoryclasslocation -> null, forceignoreunresolvedtransactions -> false, forcesynchronouscheckins -> false, identitytoken -> 1hge3hi9nk1ku80noopkx|3185ce3, idleconnectiontestperiod -> 3000, initialpoolsize -> 0, maxadministrativetasktime -> 0, maxconnectionage -> 0, maxidletime -> 300, maxidletimeexcessconnections -> 0, maxpoolsize -> 10, maxstatements -> 50, maxstatementsperconnection -> 0, minpoolsize -> 0, nesteddatasource -> com.mchange.v2.c3p0.drivermanagerdatasource@9480ea7b [ description -> null, driverclass -> null, factoryclasslocation -> null, forceusenameddriverclass -> false, identitytoken -> 1hge3hi9nk1ku80noopkx|26e664, jdbcurl -> jdbc:postgresql://localhost:5432/postgres, properties -> {user=******, password=******} ], preferredtestquery -> null, privilegespawnedthreads -> false, propertycycle -> 0, statementcachenumdeferredclosethreads -> 0, testconnectiononcheckin -> false, testconnectiononcheckout -> false, unreturnedconnectiontimeout -> 0, usestraditionalreflectiveproxies -> false; useroverrides: {} ], datasourcename -> null, extensions -> {}, factoryclasslocation -> null, identitytoken -> 1hge3hi9nk1ku80noopkx|3d02a858, numhelperthreads -> 3 ] квіт. 07, 2017 2:47:07 pm org.postgresql.driver connect severe: connection error:    org.postgresql.util.psqlexception: fatal: password authentication failed user "user"   --code omitted квіт. 07, 2017 2:47:07 pm org.postgresql.driver connect severe: connection error:    org.postgresql.util.psqlexception: fatal: password authentication failed user "user"   --code omitted   -- few attempts connect 14:47:55,009 warn [com.mchange.v2.resourcepool.basicresourcepool] - having failed acquire resource, com.mchange.v2.resourcepool.basicresourcepool@4519c236 interrupting threads waiting on resource check out. try again in response new client requests. 

after message, doesn't throw exception or return

you might consider modifying

<property name="hibernate.c3p0.acquireretryattempts" value="1"/> 

back default of 30 (or maybe higher), , try

<property name="hibernate.c3p0.breakafteracquirefailure" value="true"/> 

then, if full cycle of attempts acquire connections database fails (again, should more 1 time, or application fragile), c3p0 datasource break, , further attempts check out connection fail immediately. downside of you'll lose c3p0's capacity "self-heal" following temporary network or database outage. you'll have reconstruct datasource (or restart application) if temporary outage fails acquisition cycle.

if want best of both worlds, set hibernate.c3p0.acquireretryattempts 30-ish, leave hibernate.c3p0.breakafteracquirefailure default of false, write own custom code test availability of database. modifying test connect() function above (which needs reorganized, want create entitymanagerfactory once), might simple as...

public void connect(connectionsettingsmodel conset) throws exception {      try( connection con = drivermanager.getconnection( conset.geturl(), conset.getuser(), conset.getpassword() ) ) {         /* nothing here, really... */     } catch ( exception e ) {         system.out.println("trouble connecting dbms, please check database url, username, , password.");         throw e;       }      map<string, string> connectionproperties = new hashmap<>();     connectionproperties.put("javax.persistence.jdbc.url", conset.geturl());     connectionproperties.put("javax.persistence.jdbc.user", conset.getuser());     connectionproperties.put("javax.persistence.jdbc.password", conset.getpassword());     connectionproperties.put("hibernate.default_schema", conset.getschema());       system.out.println("before creating em");     entitymanagerfactory entitymanagerfactory = persistence.createentitymanagerfactory("postgres-connect", connectionproperties);     entitymanager entitymanager = entitymanagerfactory.createentitymanager();     system.out.println("after creating em");  }