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Diffstat (limited to 'db-4.8.30/examples_java/src/persist/txn/StoreWriter.java')
| -rw-r--r-- | db-4.8.30/examples_java/src/persist/txn/StoreWriter.java | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/db-4.8.30/examples_java/src/persist/txn/StoreWriter.java b/db-4.8.30/examples_java/src/persist/txn/StoreWriter.java new file mode 100644 index 0000000..fb8b4e5 --- /dev/null +++ b/db-4.8.30/examples_java/src/persist/txn/StoreWriter.java @@ -0,0 +1,176 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 2008-2009 Oracle. All rights reserved. + * + * $Id$ + */ + +package persist.txn; + +import com.sleepycat.db.CursorConfig; +import com.sleepycat.db.DatabaseException; +import com.sleepycat.db.DeadlockException; +import com.sleepycat.db.Environment; +import com.sleepycat.db.Transaction; + +import com.sleepycat.persist.EntityCursor; +import com.sleepycat.persist.EntityStore; +import com.sleepycat.persist.PrimaryIndex; + +import java.util.Iterator; +import java.util.Random; +import java.io.UnsupportedEncodingException; + +public class StoreWriter extends Thread +{ + private EntityStore myStore = null; + private Environment myEnv = null; + private PrimaryIndex<Integer,PayloadDataEntity> pdKey; + private Random generator = new Random(); + private boolean passTxn = false; + + + private static final int MAX_RETRY = 20; + + // Constructor. Get our handles from here + StoreWriter(Environment env, EntityStore store) + + throws DatabaseException { + myStore = store; + myEnv = env; + + // Open the data accessor. This is used to store persistent + // objects. + pdKey = myStore.getPrimaryIndex(Integer.class, + PayloadDataEntity.class); + } + + // Thread method that writes a series of objects + // to the store using transaction protection. + // Deadlock handling is demonstrated here. + public void run () { + Transaction txn = null; + + // Perform 50 transactions + for (int i=0; i<50; i++) { + + boolean retry = true; + int retry_count = 0; + // while loop is used for deadlock retries + while (retry) { + // try block used for deadlock detection and + // general exception handling + try { + + // Get a transaction + txn = myEnv.beginTransaction(null, null); + + // Write 10 PayloadDataEntity objects to the + // store for each transaction + for (int j = 0; j < 10; j++) { + // Instantiate an object + PayloadDataEntity pd = new PayloadDataEntity(); + + // Set the Object ID. This is used as the primary key. + pd.setID(i + j); + + // The thread name is used as a secondary key, and + // it is retrieved by this class's getName() method. + pd.setThreadName(getName()); + + // The last bit of data that we use is a double + // that we generate randomly. This data is not + // indexed. + pd.setDoubleData(generator.nextDouble()); + + // Do the put + pdKey.put(txn, pd); + } + + // commit + System.out.println(getName() + " : committing txn : " + i); + System.out.println(getName() + " : Found " + + countObjects(txn) + " objects in the store."); + try { + txn.commit(); + txn = null; + } catch (DatabaseException e) { + System.err.println("Error on txn commit: " + + e.toString()); + } + retry = false; + + } catch (DeadlockException de) { + System.out.println("################# " + getName() + + " : caught deadlock"); + // retry if necessary + if (retry_count < MAX_RETRY) { + System.err.println(getName() + + " : Retrying operation."); + retry = true; + retry_count++; + } else { + System.err.println(getName() + + " : out of retries. Giving up."); + retry = false; + } + } catch (DatabaseException e) { + // abort and don't retry + retry = false; + System.err.println(getName() + + " : caught exception: " + e.toString()); + System.err.println(getName() + + " : errno: " + e.getErrno()); + e.printStackTrace(); + } finally { + if (txn != null) { + try { + txn.abort(); + } catch (Exception e) { + System.err.println("Error aborting transaction: " + + e.toString()); + e.printStackTrace(); + } + } + } + } + } + } + + // This simply counts the number of objects contained in the + // store and returns the result. You can use this method + // in three ways: + // + // First call it with an active txn handle. + // + // Secondly, configure the cursor for dirty reads + // + // Third, call countObjects AFTER the writer has committed + // its transaction. + // + // If you do none of these things, the writer thread will + // self-deadlock. + private int countObjects(Transaction txn) throws DatabaseException { + int count = 0; + + CursorConfig cc = new CursorConfig(); + // This is ignored if the store is not opened with uncommitted read + // support. + cc.setReadUncommitted(true); + EntityCursor<PayloadDataEntity> cursor = pdKey.entities(txn, cc); + + try { + for (PayloadDataEntity pdi : cursor) { + count++; + } + } finally { + if (cursor != null) { + cursor.close(); + } + } + + return count; + + } +} |