| 1 | package de.uka.ipd.sdq.probespec.framework; |
| 2 | |
| 3 | import java.util.ArrayList; |
| 4 | import java.util.Collections; |
| 5 | import java.util.List; |
| 6 | |
| 7 | /** |
| 8 | * This class represents the execution context of a request. Normally the |
| 9 | * execution context of a request is the thread which processes this request. |
| 10 | * Then the thread's id is a unique identifier for this execution context. |
| 11 | * <p> |
| 12 | * A RequestContext simply wraps an identifier that represents the execution |
| 13 | * context clearly. The thread id is such an identifier. |
| 14 | * <p> |
| 15 | * In order to represent a sequence of requests so that request1 spawned |
| 16 | * request2, which in turn spawned request3 and so forth, a parent context can |
| 17 | * be specified by using constructor |
| 18 | * {@link #RequestContext(String, RequestContext)}. In this way the |
| 19 | * execution of forks can be represented. |
| 20 | * |
| 21 | * @author Faber |
| 22 | * @author Philipp Merkle |
| 23 | * |
| 24 | */ |
| 25 | public class RequestContext { |
| 26 | |
| 27 | public static final RequestContext EMPTY_REQUEST_CONTEXT = new RequestContext(""); |
| 28 | |
| 29 | // unique identifier of the request context |
| 30 | private String requestContextId; |
| 31 | |
| 32 | private RequestContext parentContext; |
| 33 | |
| 34 | private List<RequestContext> childContexts; |
| 35 | |
| 36 | /** |
| 37 | * Default Constructor. |
| 38 | * |
| 39 | * @param requestContextId |
| 40 | * the unique identifier of the request context |
| 41 | */ |
| 42 | public RequestContext(String requestContextId) { |
| 43 | this(requestContextId, null); |
| 44 | } |
| 45 | |
| 46 | /** |
| 47 | * Constructor to be used when there is a parent context. |
| 48 | * |
| 49 | * @param requestContextId |
| 50 | * the unique identifier of the request context |
| 51 | * @param parentContext |
| 52 | * the parent context of the context which is to be constructed |
| 53 | */ |
| 54 | public RequestContext(String requestContextId, RequestContext parentContext) { |
| 55 | this.requestContextId = requestContextId; |
| 56 | this.parentContext = parentContext; |
| 57 | |
| 58 | if (parentContext != null) { |
| 59 | parentContext.addChildContext(this); |
| 60 | } |
| 61 | |
| 62 | if (this.requestContextId == null) { |
| 63 | this.requestContextId = ""; |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Returns the unique identifier of the request context represented by this |
| 69 | * object. |
| 70 | * |
| 71 | * @return the request context identifier |
| 72 | */ |
| 73 | public String getRequestContextId() { |
| 74 | return requestContextId; |
| 75 | } |
| 76 | |
| 77 | public RequestContext getParentContext() { |
| 78 | return parentContext; |
| 79 | } |
| 80 | |
| 81 | private void addChildContext(RequestContext context) { |
| 82 | if (childContexts == null) { |
| 83 | childContexts = new ArrayList<RequestContext>(); |
| 84 | } |
| 85 | childContexts.add(context); |
| 86 | } |
| 87 | |
| 88 | public List<RequestContext> getChildContexts() { |
| 89 | if (childContexts == null) { |
| 90 | return null; |
| 91 | } |
| 92 | return Collections.unmodifiableList(childContexts); |
| 93 | } |
| 94 | |
| 95 | @Override |
| 96 | public int hashCode() { |
| 97 | final int prime = 31; |
| 98 | int result = 1; |
| 99 | result = prime * result |
| 100 | + ((parentContext == null) ? 0 : parentContext.hashCode()); |
| 101 | result = prime * result |
| 102 | + ((requestContextId == null) ? 0 : requestContextId.hashCode()); |
| 103 | return result; |
| 104 | } |
| 105 | |
| 106 | @Override |
| 107 | public boolean equals(Object obj) { |
| 108 | if (this == obj) { |
| 109 | return true; |
| 110 | } |
| 111 | if (obj == null) { |
| 112 | return false; |
| 113 | } |
| 114 | if (!(obj instanceof RequestContext)) { |
| 115 | return false; |
| 116 | } |
| 117 | RequestContext other = (RequestContext) obj; |
| 118 | if (parentContext == null) { |
| 119 | if (other.parentContext != null) { |
| 120 | return false; |
| 121 | } |
| 122 | } else if (!parentContext.equals(other.parentContext)) { |
| 123 | return false; |
| 124 | } |
| 125 | if (requestContextId == null) { |
| 126 | if (other.requestContextId != null) { |
| 127 | return false; |
| 128 | } |
| 129 | } else if (!requestContextId.equals(other.requestContextId)) { |
| 130 | return false; |
| 131 | } |
| 132 | return true; |
| 133 | } |
| 134 | |
| 135 | /** |
| 136 | * Appends the specified addition to the request context id and returns a |
| 137 | * new {@link RequestContext} containing the extended request context id. |
| 138 | * The parent context will be retained. |
| 139 | * |
| 140 | * @param addition |
| 141 | * the String to append |
| 142 | * @return |
| 143 | */ |
| 144 | public RequestContext append(String addition) { |
| 145 | return new RequestContext(getRequestContextId() + addition, |
| 146 | getParentContext()); |
| 147 | } |
| 148 | |
| 149 | public RequestContext rootContext() { |
| 150 | RequestContext context = this; |
| 151 | while (context.getParentContext() != null) { |
| 152 | context = context.getParentContext(); |
| 153 | } |
| 154 | return context; |
| 155 | } |
| 156 | |
| 157 | @Override |
| 158 | public String toString() { |
| 159 | return parentContext != null ? parentContext.toString() + " called " |
| 160 | + "<" + requestContextId + ">" : "<" + requestContextId + ">"; |
| 161 | } |
| 162 | |
| 163 | } |