| 1 | /* |
| 2 | * Copyright 2007 brunella ltd |
| 3 | * |
| 4 | * Licensed under the LGPL Version 3 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * |
| 7 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| 8 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 9 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 10 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| 11 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 12 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 13 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 14 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 15 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 16 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
| 17 | * THE POSSIBILITY OF SUCH DAMAGE. |
| 18 | */ |
| 19 | package sf.qof.session; |
| 20 | |
| 21 | import java.sql.Connection; |
| 22 | import java.sql.SQLException; |
| 23 | |
| 24 | /** |
| 25 | * <code>RetrySessionRunner</code> is an implementation of <code>SessionRunner</code> |
| 26 | * that runs a <code>TransactionRunnable</code> in a session context and retries |
| 27 | * if an error occured. |
| 28 | * |
| 29 | * Calling <code>execute</code> starts a new session call the <code>run</code> |
| 30 | * method of the <code>TransactionRunnable</code> and commits or rolls back |
| 31 | * the transaction on success or failure. If an error occured it retries up to |
| 32 | * <code>numberOfRetries</code> times. <code>delayInMilliSeconds</code> can be |
| 33 | * used to wait a specified amount of time between the retries. |
| 34 | * |
| 35 | * <p>Typical usage is like this:</p> |
| 36 | * |
| 37 | * <p><blockquote><pre> |
| 38 | * List<Person> personList = ... |
| 39 | * PersonUpdaterRunnable runnable = new PersonUpdaterRunnable(); |
| 40 | * Integer numberOfUpdates = |
| 41 | * new RetrySessionRunner<Integer>(runnable, "MY_CONTEXT_NAME").execute(personList, 3); |
| 42 | * </pre></blockquote></p> |
| 43 | * |
| 44 | * @param <T> the type of the result of the <code>TransactionRunnable</code>. If |
| 45 | * no result is returned this type should be <code>Void</code> |
| 46 | * |
| 47 | * @see SessionRunner |
| 48 | */ |
| 49 | public class RetrySessionRunner<T> extends BaseSessionRunner<T> { |
| 50 | |
| 51 | private int numberOfRetries; |
| 52 | private long delayInMilliSeconds; |
| 53 | private TransactionRunnable<T> runnable; |
| 54 | |
| 55 | /** |
| 56 | * Creates a <code>RetrySessionRunner</code> that creates a session |
| 57 | * from the default session context. |
| 58 | * |
| 59 | * @param runnable a <code>TransactionRunnable</code> |
| 60 | * @param numberOfRetries max number of retries |
| 61 | */ |
| 62 | public RetrySessionRunner(TransactionRunnable<T> runnable, int numberOfRetries) { |
| 63 | this(runnable, numberOfRetries, 0); |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * Creates a <code>RetrySessionRunner</code> that creates a session |
| 68 | * from the default session context. |
| 69 | * |
| 70 | * @param runnable a <code>TransactionRunnable</code> |
| 71 | * @param numberOfRetries max number of retries |
| 72 | * @param delayInMilliSeconds delay inbetween retries in milli seconds |
| 73 | */ |
| 74 | public RetrySessionRunner(TransactionRunnable<T> runnable, int numberOfRetries, long delayInMilliSeconds) { |
| 75 | this(runnable, SessionContext.DEFAULT_CONTEXT_NAME, numberOfRetries, delayInMilliSeconds); |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Creates a <code>RetrySessionRunner</code> that creates a session |
| 80 | * from the session context with the given name. |
| 81 | * |
| 82 | * @param runnable a <code>TransactionRunnable</code> |
| 83 | * @param contextName the context name |
| 84 | * @param numberOfRetries max number of retries |
| 85 | */ |
| 86 | public RetrySessionRunner(TransactionRunnable<T> runnable, String contextName, int numberOfRetries) { |
| 87 | this(runnable, contextName, numberOfRetries, 0); |
| 88 | } |
| 89 | |
| 90 | /** |
| 91 | * Creates a <code>RetrySessionRunner</code> that creates a session |
| 92 | * from the session context with the given name. |
| 93 | * |
| 94 | * @param runnable a <code>TransactionRunnable</code> |
| 95 | * @param contextName the context name |
| 96 | * @param numberOfRetries max number of retries |
| 97 | * @param delayInMilliSeconds delay inbetween retries in milli seconds |
| 98 | */ |
| 99 | public RetrySessionRunner(TransactionRunnable<T> runnable, String contextName, int numberOfRetries, long delayInMilliSeconds) { |
| 100 | super(contextName); |
| 101 | this.runnable = runnable; |
| 102 | this.numberOfRetries = numberOfRetries; |
| 103 | this.delayInMilliSeconds = delayInMilliSeconds; |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * @see SessionRunner#execute(Object[]) |
| 108 | */ |
| 109 | @Override |
| 110 | public T execute(Object... arguments) throws SystemException { |
| 111 | T result = null; |
| 112 | int tries = 0; |
| 113 | boolean success = false; |
| 114 | while (!success && tries++ <= numberOfRetries) { |
| 115 | try { |
| 116 | result = super.execute(arguments); |
| 117 | success = true; |
| 118 | } catch (SystemException e) { |
| 119 | if (tries > numberOfRetries) { |
| 120 | throw e; |
| 121 | } |
| 122 | } |
| 123 | if (!success && delayInMilliSeconds > 0) { |
| 124 | try { |
| 125 | Thread.sleep(delayInMilliSeconds); |
| 126 | } catch (InterruptedException e) {} |
| 127 | } |
| 128 | } |
| 129 | return result; |
| 130 | } |
| 131 | |
| 132 | @Override |
| 133 | protected T run(Connection connection, Object... arguments) throws SQLException { |
| 134 | return runnable.run(connection, arguments); |
| 135 | } |
| 136 | } |