1 /* ============================================================
2 * JRobin : Pure java implementation of RRDTool's functionality
3 * ============================================================
4 *
5 * Project Info: http://www.jrobin.org
6 * Project Lead: Sasa Markovic (saxon@jrobin.org);
7 *
8 * (C) Copyright 2003-2005, by Sasa Markovic.
9 *
10 * This library is free software; you can redistribute it and/or modify it under the terms
11 * of the GNU Lesser General Public License as published by the Free Software Foundation;
12 * either version 2.1 of the License, or (at your option) any later version.
13 *
14 * Developers: Sasa Markovic (saxon@jrobin.org)
15 *
16 *
17 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
18 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
19 * See the GNU Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public License along with this
22 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
23 * Boston, MA 02111-1307, USA.
24 */
25
26 package org.jrobin.core;
27
28 import java.io.IOException;
29
30 /**
31 * Class to represent RRD header. Header information is mainly static (once set, it
32 * cannot be changed), with the exception of last update time (this value is changed whenever
33 * RRD gets updated).<p>
34 * <p/>
35 * Normally, you don't need to manipulate the Header object directly - JRobin framework
36 * does it for you.<p>
37 *
38 * @author <a href="mailto:saxon@jrobin.org">Sasa Markovic</a>*
39 */
40 public class Header implements RrdUpdater {
41 static final int SIGNATURE_LENGTH = 2;
42 static final String SIGNATURE = "JR";
43
44 static final String DEFAULT_SIGNATURE = "JRobin, version 0.1";
45 static final String RRDTOOL_VERSION = "0001";
46
47 private RrdDb parentDb;
48
49 private RrdString signature;
50 private RrdLong step;
51 private RrdInt dsCount, arcCount;
52 private RrdLong lastUpdateTime;
53
54 Header(RrdDb parentDb, RrdDef rrdDef) throws IOException {
55 boolean shouldInitialize = rrdDef != null;
56 this.parentDb = parentDb;
57 signature = new RrdString(this); // NOT constant, may be cached
58 step = new RrdLong(this, true); // constant, may be cached
59 dsCount = new RrdInt(this, true); // constant, may be cached
60 arcCount = new RrdInt(this, true); // constant, may be cached
61 lastUpdateTime = new RrdLong(this);
62 if (shouldInitialize) {
63 signature.set(DEFAULT_SIGNATURE);
64 step.set(rrdDef.getStep());
65 dsCount.set(rrdDef.getDsCount());
66 arcCount.set(rrdDef.getArcCount());
67 lastUpdateTime.set(rrdDef.getStartTime());
68 }
69 }
70
71 Header(RrdDb parentDb, DataImporter reader) throws IOException, RrdException {
72 this(parentDb, (RrdDef) null);
73 String version = reader.getVersion();
74 if (!version.equals(RRDTOOL_VERSION)) {
75 throw new RrdException("Could not unserilalize xml version " + version);
76 }
77 signature.set(DEFAULT_SIGNATURE);
78 step.set(reader.getStep());
79 dsCount.set(reader.getDsCount());
80 arcCount.set(reader.getArcCount());
81 lastUpdateTime.set(reader.getLastUpdateTime());
82 }
83
84 /**
85 * Returns RRD signature. Initially, the returned string will be
86 * of the form <b><i>JRobin, version x.x</i></b>. Note: RRD format did not
87 * change since Jrobin 1.0.0 release (and probably never will).
88 *
89 * @return RRD signature
90 * @throws IOException Thrown in case of I/O error
91 */
92 public String getSignature() throws IOException {
93 return signature.get();
94 }
95
96 public String getInfo() throws IOException {
97 return getSignature().substring(SIGNATURE_LENGTH);
98 }
99
100 public void setInfo(String info) throws IOException {
101 if (info != null && info.length() > 0) {
102 signature.set(SIGNATURE + info);
103 }
104 else {
105 signature.set(SIGNATURE);
106 }
107 }
108
109 /**
110 * Returns the last update time of the RRD.
111 *
112 * @return Timestamp (Unix epoch, no milliseconds) corresponding to the last update time.
113 * @throws IOException Thrown in case of I/O error
114 */
115 public long getLastUpdateTime() throws IOException {
116 return lastUpdateTime.get();
117 }
118
119 /**
120 * Returns primary RRD time step.
121 *
122 * @return Primary time step in seconds
123 * @throws IOException Thrown in case of I/O error
124 */
125 public long getStep() throws IOException {
126 return step.get();
127 }
128
129 /**
130 * Returns the number of datasources defined in the RRD.
131 *
132 * @return Number of datasources defined
133 * @throws IOException Thrown in case of I/O error
134 */
135 public int getDsCount() throws IOException {
136 return dsCount.get();
137 }
138
139 /**
140 * Returns the number of archives defined in the RRD.
141 *
142 * @return Number of archives defined
143 * @throws IOException Thrown in case of I/O error
144 */
145 public int getArcCount() throws IOException {
146 return arcCount.get();
147 }
148
149 void setLastUpdateTime(long lastUpdateTime) throws IOException {
150 this.lastUpdateTime.set(lastUpdateTime);
151 }
152
153 String dump() throws IOException {
154 return "== HEADER ==\n" +
155 "signature:" + getSignature() +
156 " lastUpdateTime:" + getLastUpdateTime() +
157 " step:" + getStep() +
158 " dsCount:" + getDsCount() +
159 " arcCount:" + getArcCount() + "\n";
160 }
161
162 void appendXml(XmlWriter writer) throws IOException {
163 writer.writeComment(signature.get());
164 writer.writeTag("version", RRDTOOL_VERSION);
165 writer.writeComment("Seconds");
166 writer.writeTag("step", step.get());
167 writer.writeComment(Util.getDate(lastUpdateTime.get()));
168 writer.writeTag("lastupdate", lastUpdateTime.get());
169 }
170
171 /**
172 * Copies object's internal state to another Header object.
173 *
174 * @param other New Header object to copy state to
175 * @throws IOException Thrown in case of I/O error
176 * @throws RrdException Thrown if supplied argument is not a Header object
177 */
178 public void copyStateTo(RrdUpdater other) throws IOException, RrdException {
179 if (!(other instanceof Header)) {
180 throw new RrdException(
181 "Cannot copy Header object to " + other.getClass().getName());
182 }
183 Header header = (Header) other;
184 header.signature.set(signature.get());
185 header.lastUpdateTime.set(lastUpdateTime.get());
186 }
187
188 /**
189 * Returns the underlying storage (backend) object which actually performs all
190 * I/O operations.
191 *
192 * @return I/O backend object
193 */
194 public RrdBackend getRrdBackend() {
195 return parentDb.getRrdBackend();
196 }
197
198 boolean isJRobinHeader() throws IOException {
199 return signature.get().startsWith(SIGNATURE);
200 }
201
202 void validateHeader() throws IOException, RrdException {
203 if (!isJRobinHeader()) {
204 String msg = "Invalid file header. File [" + parentDb.getCanonicalPath() + "] is not a JRobin RRD file";
205 throw new RrdException(msg);
206 }
207 }
208
209 /**
210 * Required to implement RrdUpdater interface. You should never call this method directly.
211 *
212 * @return Allocator object
213 */
214 public RrdAllocator getRrdAllocator() {
215 return parentDb.getRrdAllocator();
216 }
217 }
218