1 | package de.uka.ipd.sdq.probespec.framework; |
2 | |
3 | import java.util.ArrayList; |
4 | import java.util.HashMap; |
5 | import java.util.List; |
6 | import java.util.Map.Entry; |
7 | |
8 | /** |
9 | * The blackboard is a mediator between entities producing samples ( |
10 | * {@link ProbeSetSample}s) and entities consuming samples. Producers offer |
11 | * their samples by calling {@link #addSample(ProbeSetSample)}. Consumers |
12 | * implement the {@link IBlackboardListener} interface and register themselves |
13 | * at the blackboard. Afterwards they receive all samples they are interested |
14 | * in. |
15 | * <p> |
16 | * Consumers can express their interest by passing one or more topics while |
17 | * registering as observer. When no topics are passed, the consumer gets |
18 | * notified of all arriving samples. |
19 | * <p> |
20 | * Published samples can be stored at the blackboard. When a consumer gets |
21 | * notified of a new samples, it has to vote whether the blackboard is supposed |
22 | * to keep (store) the sample. A single {@link BlackboardVote#RETAIN}-vote is |
23 | * sufficient to store the sample. Only when all consumers vote |
24 | * {@link BlackboardVote#DISCARD} the sample gets discarded. |
25 | * <p> |
26 | * Samples are unique identified by a pair of a ProbeSetID and a |
27 | * {@link RequestContext}, encapsulated by a {@link ProbeSetAndRequestContext}. |
28 | * Thereby the blackboard can store several samples originating from the same |
29 | * ProbeSet, one for each RequestContext. |
30 | * |
31 | * @author Faber |
32 | * @author Philipp Merkle |
33 | * |
34 | */ |
35 | public class SampleBlackboard implements ISampleBlackboard { |
36 | |
37 | private List<IBlackboardListener> listeners; |
38 | |
39 | private HashMap<Integer, ArrayList<IBlackboardListener>> topicToListenersMap; |
40 | |
41 | // stores the samples |
42 | // maps RequestContext to map (ProbeSetAndRequestContext -> ProbeSetSample) |
43 | private HashMap<RequestContext, HashMap<ProbeSetAndRequestContext, ProbeSetSample>> sampleMap = new HashMap<RequestContext, HashMap<ProbeSetAndRequestContext, ProbeSetSample>>(); |
44 | |
45 | public SampleBlackboard() { |
46 | listeners = new ArrayList<IBlackboardListener>(); |
47 | topicToListenersMap = new HashMap<Integer, ArrayList<IBlackboardListener>>(); |
48 | } |
49 | |
50 | |
51 | public void addSample(ProbeSetSample pss) { |
52 | // notify listeners and obtain deletion vote |
53 | BlackboardVote deletionVote = fireSampleArrived(pss); |
54 | |
55 | // retain sample if at least one RETAIN-vote exists |
56 | if (deletionVote.equals(BlackboardVote.RETAIN)) { |
57 | RequestContext context = pss.getProbeSetAndRequestContext() |
58 | .getCtxID(); |
59 | HashMap<ProbeSetAndRequestContext, ProbeSetSample> contextMap = sampleMap |
60 | .get(context); |
61 | // create hash map for request context, if not done yet |
62 | if (contextMap == null) { |
63 | contextMap = new HashMap<ProbeSetAndRequestContext, ProbeSetSample>(); |
64 | sampleMap.put(context, contextMap); |
65 | } |
66 | contextMap.put(pss.getProbeSetAndRequestContext(), pss); |
67 | } |
68 | } |
69 | |
70 | |
71 | public void deleteSample(ProbeSetAndRequestContext pss) { |
72 | sampleMap.get(pss.getCtxID()).remove(pss); |
73 | } |
74 | |
75 | |
76 | public void deleteSamplesInRequestContext(RequestContext requestContext) { |
77 | // delete samples in child contexts, if there are any |
78 | if (requestContext.getChildContexts() != null) { |
79 | for (RequestContext child : requestContext.getChildContexts()) { |
80 | deleteSamplesInRequestContext(child); |
81 | } |
82 | } |
83 | |
84 | HashMap<ProbeSetAndRequestContext, ProbeSetSample> contextMap = sampleMap |
85 | .get(requestContext); |
86 | if (contextMap != null) { |
87 | contextMap.clear(); |
88 | sampleMap.remove(requestContext); |
89 | } |
90 | } |
91 | |
92 | /** |
93 | * {@inheritDoc} |
94 | * <p> |
95 | * If no ProbeSetSample can be found for the RequestContext and the |
96 | * RequestContext has a parent context, the search will be performed for |
97 | * that parent context too. This continues recursively until a |
98 | * RequestContext is reached that does not have a parent context. |
99 | * <p> |
100 | * This recursive search is useful for e.g. finding the start ProbeSetSample |
101 | * (taken before a fork) for a given end ProbeSetSample (taken within a |
102 | * fork). |
103 | * |
104 | * @param probeSetSampleID |
105 | * the encapsulated probeId and RequestContextID |
106 | * @return the ProbeSetSample for the probeSetSampleID, if there is any; |
107 | * else null. |
108 | */ |
109 | public ProbeSetSample getSample(ProbeSetAndRequestContext probeSetSampleID) { |
110 | // try to find the ProbeSetSample in the specified context |
111 | ProbeSetSample sample = obtainSample(probeSetSampleID); |
112 | if (sample != null) { |
113 | return sample; |
114 | } |
115 | |
116 | // try to find the ProbeSetSample in a parent context |
117 | RequestContext ctx = probeSetSampleID.getCtxID().getParentContext(); |
118 | Integer probeSetID = probeSetSampleID.getProbeSetID(); |
119 | while (ctx != null) { |
120 | ProbeSetAndRequestContext pssID = new ProbeSetAndRequestContext( |
121 | probeSetID, ctx); |
122 | ProbeSetSample pss = obtainSample(pssID); |
123 | if (pss != null) { |
124 | return pss; |
125 | } |
126 | ctx = ctx.getParentContext(); |
127 | } |
128 | return null; |
129 | } |
130 | |
131 | /** |
132 | * Returns the {@link ProbeSetSample} for the specified |
133 | * {@link ProbeSetAndRequestContext}. |
134 | * |
135 | * @param probeSetSampleID |
136 | * @return |
137 | */ |
138 | private ProbeSetSample obtainSample( |
139 | ProbeSetAndRequestContext probeSetSampleID) { |
140 | HashMap<ProbeSetAndRequestContext, ProbeSetSample> contextMap = sampleMap |
141 | .get(probeSetSampleID.getCtxID()); |
142 | if (contextMap != null) { |
143 | return contextMap.get(probeSetSampleID); |
144 | } |
145 | return null; |
146 | } |
147 | |
148 | public int size() { |
149 | int i = 0; |
150 | for (Entry<RequestContext, HashMap<ProbeSetAndRequestContext, ProbeSetSample>> e : sampleMap |
151 | .entrySet()) { |
152 | i += e.getValue().size(); |
153 | } |
154 | return i; |
155 | } |
156 | |
157 | public void addBlackboardListener(IBlackboardListener l, Integer... topics) { |
158 | if (topics.length == 0) { |
159 | listeners.add(l); |
160 | } else { |
161 | // add listener for each topic |
162 | for (Integer t : topics) { |
163 | ArrayList<IBlackboardListener> listeners = topicToListenersMap |
164 | .get(t); |
165 | if (listeners == null) { |
166 | listeners = new ArrayList<IBlackboardListener>(); |
167 | topicToListenersMap.put(t, listeners); |
168 | } |
169 | listeners.add(l); |
170 | } |
171 | } |
172 | |
173 | } |
174 | |
175 | /** |
176 | * Notifies all specified listeners of a new {@link ProbeSetSample}. |
177 | * |
178 | * @param pss |
179 | * @param listeners |
180 | * the listeners that are to be notified |
181 | * @return {@link BlackboardVote#RETAIN} when the sample has to be stored; |
182 | * {@link BlackboardVote#DISCARD} else. |
183 | */ |
184 | private BlackboardVote fireSampleArrived(ProbeSetSample pss, |
185 | List<IBlackboardListener> listeners) { |
186 | // private BlackboardVote fireSampleArrived(ProbeSetSample pss) { |
187 | BlackboardVote deletionVote = BlackboardVote.DISCARD; |
188 | for (IBlackboardListener l : listeners) { |
189 | if (l.sampleArrived(pss).equals(BlackboardVote.RETAIN)) { |
190 | deletionVote = BlackboardVote.RETAIN; |
191 | } |
192 | } |
193 | return deletionVote; |
194 | } |
195 | |
196 | /** |
197 | * Notifies all listeners of a new {@link ProbeSetSample}. Both listeners |
198 | * that are not registered for a specific topic and listeners interested in |
199 | * one or more topics get notified of the new ProbeSetSample. |
200 | * |
201 | * @param pss |
202 | * @return {@link BlackboardVote#RETAIN} when the sample has to be stored; |
203 | * {@link BlackboardVote#DISCARD} else. |
204 | */ |
205 | private BlackboardVote fireSampleArrived(ProbeSetSample pss) { |
206 | // notify listeners that are not registered for a specific topic |
207 | BlackboardVote firstDeletionVote = fireSampleArrived(pss, listeners); |
208 | |
209 | // notify listeners that are registered for the sample's topic |
210 | Integer topic = pss.getProbeSetAndRequestContext().getProbeSetID(); |
211 | List<IBlackboardListener> listeners = topicToListenersMap.get(topic); |
212 | BlackboardVote secondDeletionVote = null; |
213 | if (listeners != null) { |
214 | secondDeletionVote = fireSampleArrived(pss, listeners); |
215 | } |
216 | |
217 | if (firstDeletionVote.equals(BlackboardVote.DISCARD) |
218 | && (secondDeletionVote == null || secondDeletionVote |
219 | .equals(BlackboardVote.DISCARD))) { |
220 | return BlackboardVote.DISCARD; |
221 | } |
222 | return BlackboardVote.RETAIN; |
223 | } |
224 | |
225 | } |