Public Member Functions | |
| ParallelDB_LPRF (VirtualDatabase vdb) throws Exception | |
| DatabaseBackend | chooseBackendForReadRequest (AbstractRequest request) throws SQLException |
| DatabaseBackend | chooseBackendForWriteRequest (AbstractWriteRequest request) throws SQLException |
| String | getInformation () |
| String | getParallelDBXml () |
Definition at line 45 of file ParallelDB_LPRF.java.
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Creates a new
Definition at line 54 of file ParallelDB_LPRF.java. 00055 {
00056 super(vdb);
00057 }
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Implements org.objectweb.cjdbc.controller.loadbalancer.paralleldb.ParallelDB. Definition at line 62 of file ParallelDB_LPRF.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.backend.DatabaseBackend.getPendingRequests(), org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.getSQLShortFormLength(), and org.objectweb.cjdbc.controller.backend.DatabaseBackend.isReadEnabled(). 00064 {
00065 // Choose a backend
00066 try
00067 {
00068 vdb.acquireReadLockBackendLists();
00069 }
00070 catch (InterruptedException e)
00071 {
00072 String msg = Translate.get(
00073 "loadbalancer.backendlist.acquire.readlock.failed", e);
00074 logger.error(msg);
00075 throw new SQLException(msg);
00076 }
00077
00078 DatabaseBackend backend = null; // The backend that will execute the query
00079
00080 // Note that vdb lock is released in the finally clause of this try/catch
00081 // block
00082 try
00083 {
00084 ArrayList backends = vdb.getBackends();
00085 int size = backends.size();
00086
00087 if (size == 0)
00088 throw new SQLException(Translate.get(
00089 "loadbalancer.execute.no.backend.available", request.getId()));
00090
00091 // Choose the backend that has the least pending requests
00092 int leastRequests = 0;
00093 for (int i = 0; i < size; i++)
00094 {
00095 DatabaseBackend b = (DatabaseBackend) backends.get(i);
00096 if (b.isReadEnabled())
00097 {
00098 int pending = b.getPendingRequests().size();
00099 if ((backend == null) || (pending < leastRequests))
00100 {
00101 backend = b;
00102 if (pending == 0)
00103 break; // Stop here we will never find a less loaded node
00104 else
00105 leastRequests = pending;
00106 }
00107 }
00108 }
00109
00110 if (backend == null)
00111 throw new SQLException(Translate.get(
00112 "loadbalancer.execute.no.backend.enabled", request.getId()));
00113 }
00114 catch (RuntimeException e)
00115 {
00116 String msg = Translate.get("loadbalancer.execute.find.backend.failed",
00117 new String[]{request.getSQLShortForm(vdb.getSQLShortFormLength()),
00118 e.getMessage()});
00119 logger.error(msg, e);
00120 throw new SQLException(msg);
00121 }
00122 finally
00123 {
00124 vdb.releaseReadLockBackendLists();
00125 }
00126
00127 return backend;
00128 }
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Implements org.objectweb.cjdbc.controller.loadbalancer.paralleldb.ParallelDB. Definition at line 133 of file ParallelDB_LPRF.java. References org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.acquireReadLockBackendLists(), org.objectweb.cjdbc.controller.virtualdatabase.VirtualDatabase.getBackends(), org.objectweb.cjdbc.controller.backend.DatabaseBackend.getPendingRequests(), org.objectweb.cjdbc.controller.backend.DatabaseBackend.isDisabling(), and org.objectweb.cjdbc.controller.backend.DatabaseBackend.isWriteEnabled(). 00135 {
00136 // Choose a backend
00137 try
00138 {
00139 vdb.acquireReadLockBackendLists();
00140 }
00141 catch (InterruptedException e)
00142 {
00143 String msg = Translate.get(
00144 "loadbalancer.backendlist.acquire.readlock.failed", e);
00145 logger.error(msg);
00146 throw new SQLException(msg);
00147 }
00148
00149 DatabaseBackend backend = null; // The backend that will execute the query
00150
00151 // Note that vdb lock is released in the finally clause of this try/catch
00152 // block
00153 try
00154 {
00155 ArrayList backends = vdb.getBackends();
00156 int size = backends.size();
00157
00158 if (size == 0)
00159 throw new SQLException(Translate.get(
00160 "loadbalancer.execute.no.backend.available", request.getId()));
00161
00162 // Choose the backend that has the least pending requests
00163 int leastRequests = 0;
00164 for (int i = 0; i < size; i++)
00165 {
00166 DatabaseBackend b = (DatabaseBackend) backends.get(i);
00167 if (b.isWriteEnabled() && !b.isDisabling())
00168 {
00169 int pending = b.getPendingRequests().size();
00170 if ((backend == null) || (pending < leastRequests))
00171 {
00172 backend = b;
00173 if (pending == 0)
00174 break; // Stop here we will never find a less loaded node
00175 else
00176 leastRequests = pending;
00177 }
00178 }
00179 }
00180
00181 if (backend == null)
00182 {
00183 throw new SQLException(Translate.get(
00184 "loadbalancer.execute.no.backend.enabled", request.getId()));
00185 }
00186 }
00187 catch (RuntimeException e)
00188 {
00189 String msg = Translate.get("loadbalancer.execute.find.backend.failed",
00190 new String[]{request.getSQLShortForm(vdb.getSQLShortFormLength()),
00191 e.getMessage()});
00192 logger.error(msg, e);
00193 throw new SQLException(msg);
00194 }
00195 finally
00196 {
00197 vdb.releaseReadLockBackendLists();
00198 }
00199
00200 return backend;
00201 }
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Implements org.objectweb.cjdbc.controller.loadbalancer.AbstractLoadBalancer. Definition at line 206 of file ParallelDB_LPRF.java. 00207 {
00208 // We don't lock since we don't need a top accurate value
00209 int size = vdb.getBackends().size();
00210
00211 if (size == 0)
00212 return "ParallelDB Least Pending Request First Request load balancer: !!!Warning!!! No backend nodes found\n";
00213 else
00214 return "ParallelDB Least Pending Request First Request load balancer ("
00215 + size + " backends)\n";
00216 }
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Implements org.objectweb.cjdbc.controller.loadbalancer.paralleldb.ParallelDB. Definition at line 221 of file ParallelDB_LPRF.java. 00222 {
00223 return "<" + DatabasesXmlTags.ELT_ParallelDB_LeastPendingRequestsFirst
00224 + "/>";
00225 }
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1.3.9.1