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13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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25 
26 package sun.jvmstat.perfdata.monitor.protocol.local;
27 
28 import sun.misc.Perf;
29 import sun.jvmstat.monitor.*;
30 import sun.jvmstat.perfdata.monitor.*;
31 import java.util.*;
32 import java.io.*;
33 import java.nio.ByteBuffer;
34 import java.nio.channels.FileChannel;
35 import java.lang.reflect.Constructor;
36 import java.security.AccessController;
37 
38 /**
39  * The concrete PerfDataBuffer implementation for the <em>local:</em>
40  * protocol for the HotSpot PerfData monitoring implementation.
41  * <p>
42  * This class is responsible for acquiring access to the shared memory
43  * instrumentation buffer for the target HotSpot Java Virtual Machine.
44  *
45  * @author Brian Doherty
46  * @since 1.5
47  */
48 // Suppreess unchecked conversion warning at line 34.
49 //@SuppressWarnings("unchecked")
50 public class PerfDataBuffer extends AbstractPerfDataBuffer {
51     private static final Perf perf = AccessController.doPrivileged(new Perf.GetPerfAction());
52 
53     /**
54      * Create a PerfDataBuffer instance for accessing the specified
55      * instrumentation buffer.
56      *
57      * @param vmid the <em>local:</em> URI specifying the target JVM.
58      *
59      * @throws MonitorException
60      */
PerfDataBuffer(VmIdentifier vmid)61     public PerfDataBuffer(VmIdentifier vmid) throws MonitorException {
62         try {
63             // Try 1.4.2 and later first
64             ByteBuffer bb = perf.attach(vmid.getLocalVmId(), vmid.getMode());
65             createPerfDataBuffer(bb, vmid.getLocalVmId());
66 
67         } catch (IllegalArgumentException e) {
68             // now try 1.4.1 by attempting to directly map the files.
69             try {
70                 String filename = PerfDataFile.getTempDirectory()
71                                   + PerfDataFile.dirNamePrefix
72                                   + Integer.toString(vmid.getLocalVmId());
73 
74                 File f = new File(filename);
75 
76                 FileChannel fc = new RandomAccessFile(f, "r").getChannel();
77                 ByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0L,
78                                        (int)fc.size());
79                 fc.close();
80                 createPerfDataBuffer(bb, vmid.getLocalVmId());
81 
82             } catch (FileNotFoundException e2) {
83                 // re-throw the exception from the 1.4.2 attach method
84                 throw new MonitorException(vmid.getLocalVmId() + " not found",
85                                            e);
86             } catch (IOException e2) {
87                 throw new MonitorException("Could not map 1.4.1 file for "
88                                            + vmid.getLocalVmId(), e2);
89             }
90         } catch (IOException e) {
91             throw new MonitorException("Could not attach to "
92                                        + vmid.getLocalVmId(), e);
93         }
94     }
95 }
96