Public Member Functions | |
| ParallelDB_RR (VirtualDatabase vdb) throws Exception | |
| DatabaseBackend | chooseBackendForReadRequest (AbstractRequest request) throws SQLException |
| DatabaseBackend | chooseBackendForWriteRequest (AbstractWriteRequest request) throws SQLException |
| String | getInformation () |
| String | getParallelDBXml () |
Definition at line 44 of file ParallelDB_RR.java.
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Creates a new
Definition at line 55 of file ParallelDB_RR.java. 00056 {
00057 super(vdb);
00058 }
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Choose a backend using a round-robin algorithm for read request execution.
Implements org.objectweb.cjdbc.controller.loadbalancer.paralleldb.ParallelDB. Definition at line 67 of file ParallelDB_RR.java. References org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.acquireReadLockBackendLists(), org.objectweb.cjdbc.common.log.Trace.error(), org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.getBackends(), org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.getSQLShortFormLength(), and org.objectweb.cjdbc.controller.backend.DatabaseBackend.isReadEnabled(). 00069 {
00070 // Choose a backend
00071 try
00072 {
00073 vdb.acquireReadLockBackendLists();
00074 }
00075 catch (InterruptedException e)
00076 {
00077 String msg = Translate.get(
00078 "loadbalancer.backendlist.acquire.readlock.failed", e);
00079 logger.error(msg);
00080 throw new SQLException(msg);
00081 }
00082
00083 DatabaseBackend backend = null; // The backend that will execute the query
00084
00085 // Note that vdb lock is released in the finally clause of this try/catch
00086 // block
00087 try
00088 {
00089 ArrayList backends = vdb.getBackends();
00090 int size = backends.size();
00091
00092 if (size == 0)
00093 throw new SQLException(Translate.get(
00094 "loadbalancer.execute.no.backend.available", request.getId()));
00095
00096 // Take the next backend
00097 int maxTries = size;
00098 synchronized (this)
00099 {
00100 do
00101 {
00102 index = (index + 1) % size;
00103 backend = (DatabaseBackend) backends.get(index);
00104 maxTries--;
00105 }
00106 while ((!backend.isReadEnabled() && maxTries >= 0));
00107 }
00108
00109 if (maxTries < 0)
00110 throw new SQLException(Translate.get(
00111 "loadbalancer.execute.no.backend.enabled", request.getId()));
00112 }
00113 catch (RuntimeException e)
00114 {
00115 String msg = Translate.get("loadbalancer.execute.find.backend.failed",
00116 new String[]{request.getSQLShortForm(vdb.getSQLShortFormLength()),
00117 e.getMessage()});
00118 logger.error(msg, e);
00119 throw new SQLException(msg);
00120 }
00121 finally
00122 {
00123 vdb.releaseReadLockBackendLists();
00124 }
00125 return backend;
00126 }
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Choose a backend using a round-robin algorithm for write request execution.
Implements org.objectweb.cjdbc.controller.loadbalancer.paralleldb.ParallelDB. Definition at line 135 of file ParallelDB_RR.java. References org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.acquireReadLockBackendLists(), org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.getBackends(), org.objectweb.cjdbc.controller.backend.DatabaseBackend.isDisabling(), and org.objectweb.cjdbc.controller.backend.DatabaseBackend.isWriteEnabled(). 00137 {
00138 // Choose a backend
00139 try
00140 {
00141 vdb.acquireReadLockBackendLists();
00142 }
00143 catch (InterruptedException e)
00144 {
00145 String msg = Translate.get(
00146 "loadbalancer.backendlist.acquire.readlock.failed", e);
00147 logger.error(msg);
00148 throw new SQLException(msg);
00149 }
00150
00151 DatabaseBackend backend = null; // The backend that will execute the query
00152
00153 // Note that vdb lock is released in the finally clause of this try/catch
00154 // block
00155 try
00156 {
00157 ArrayList backends = vdb.getBackends();
00158 int size = backends.size();
00159
00160 if (size == 0)
00161 throw new SQLException(Translate.get(
00162 "loadbalancer.execute.no.backend.available", request.getId()));
00163
00164 // Take the next backend
00165 int maxTries = size;
00166 synchronized (this)
00167 {
00168 do
00169 {
00170 index = (index + 1) % size;
00171 backend = (DatabaseBackend) backends.get(index);
00172 maxTries--;
00173 }
00174 while ((!backend.isWriteEnabled() || backend.isDisabling())
00175 && (maxTries >= 0));
00176 }
00177
00178 if (maxTries < 0)
00179 throw new SQLException(Translate.get(
00180 "loadbalancer.execute.no.backend.enabled", request.getId()));
00181 }
00182 catch (RuntimeException e)
00183 {
00184 String msg = Translate.get("loadbalancer.execute.find.backend.failed",
00185 new String[]{request.getSQLShortForm(vdb.getSQLShortFormLength()),
00186 e.getMessage()});
00187 logger.error(msg, e);
00188 throw new SQLException(msg);
00189 }
00190 finally
00191 {
00192 vdb.releaseReadLockBackendLists();
00193 }
00194 return backend;
00195 }
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Implements org.objectweb.cjdbc.controller.loadbalancer.AbstractLoadBalancer. Definition at line 200 of file ParallelDB_RR.java. 00201 {
00202 // We don't lock since we don't need a top accurate value
00203 int size = vdb.getBackends().size();
00204
00205 if (size == 0)
00206 return "ParallelDB Round-Robin Request load balancer: !!!Warning!!! No backend nodes found\n";
00207 else
00208 return "ParallelDB Round-Robin Request load balancer (" + size
00209 + " backends)\n";
00210 }
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Implements org.objectweb.cjdbc.controller.loadbalancer.paralleldb.ParallelDB. Definition at line 215 of file ParallelDB_RR.java. 00216 {
00217 return "<" + DatabasesXmlTags.ELT_ParallelDB_RoundRobin + "/>";
00218 }
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1.3.9.1