Add PDH counter lookup and enumeration functions #973
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| /* Copyright (c) 2018 Daniel Widdis, All Rights Reserved | ||
| * | ||
| * The contents of this file is dual-licensed under 2 | ||
| * alternative Open Source/Free licenses: LGPL 2.1 or later and | ||
| * Apache License 2.0. (starting with JNA version 4.0.0). | ||
| * | ||
| * You can freely decide which license you want to apply to | ||
| * the project. | ||
| * | ||
| * You may obtain a copy of the LGPL License at: | ||
| * | ||
| * http://www.gnu.org/licenses/licenses.html | ||
| * | ||
| * A copy is also included in the downloadable source code package | ||
| * containing JNA, in file "LGPL2.1". | ||
| * | ||
| * You may obtain a copy of the Apache License at: | ||
| * | ||
| * http://www.apache.org/licenses/ | ||
| * | ||
| * A copy is also included in the downloadable source code package | ||
| * containing JNA, in file "AL2.0". | ||
| */ | ||
| package com.sun.jna.platform.win32; | ||
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| import java.util.ArrayList; | ||
| import java.util.LinkedList; | ||
| import java.util.List; | ||
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| import com.sun.jna.Memory; | ||
| import com.sun.jna.Native; | ||
| import com.sun.jna.platform.win32.WinDef.DWORD; | ||
| import com.sun.jna.platform.win32.WinDef.DWORDByReference; | ||
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| /** | ||
| * Pdh utility API. | ||
| * | ||
| * @author widdis[at]gmail[dot]com | ||
| */ | ||
| public abstract class PdhUtil { | ||
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| /** | ||
| * Utility method to call Pdh's PdhLookupPerfNameByIndex that allocates the | ||
| * required memory for the szNameBuffer parameter based on the type mapping | ||
| * used, calls to PdhLookupPerfNameByIndex, and returns the received string. | ||
| * | ||
| * @param szMachineName | ||
| * Null-terminated string that specifies the name of the computer | ||
| * where the specified performance object or counter is located. | ||
| * The computer name can be specified by the DNS name or the IP | ||
| * address. If NULL, the function uses the local computer. | ||
| * @param dwNameIndex | ||
| * Index of the performance object or counter. | ||
| * @return Returns the name of the performance object or counter. | ||
| */ | ||
| public static String PdhLookupPerfNameByIndex(String szMachineName, int dwNameIndex) { | ||
| int charToBytes = Boolean.getBoolean("w32.ascii") ? 1 : Native.WCHAR_SIZE; | ||
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| // Call once to get required buffer size | ||
| DWORDByReference pcchNameBufferSize = new DWORDByReference(new DWORD(0)); | ||
| Pdh.INSTANCE.PdhLookupPerfNameByIndex(null, dwNameIndex, null, pcchNameBufferSize); | ||
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| // Allocate buffer and call again | ||
| Memory mem = new Memory(pcchNameBufferSize.getValue().intValue() * charToBytes); | ||
| Pdh.INSTANCE.PdhLookupPerfNameByIndex(null, dwNameIndex, mem, pcchNameBufferSize); | ||
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| // Convert buffer to Java String | ||
| if (charToBytes == 1) { | ||
| return mem.getString(0); | ||
| } else { | ||
| return mem.getWideString(0); | ||
| } | ||
| } | ||
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| /** | ||
| * Utility method to call Pdh's PdhEnumObjectItems that allocates the | ||
| * required memory for the mszCounterList and mszInstanceList parameters | ||
| * based on the type mapping used, calls to PdhEnumObjectItems, and returns | ||
| * the received lists of strings. | ||
| * | ||
| * @param szDataSource | ||
| * String that specifies the name of the log file used to | ||
| * enumerate the counter and instance names. If NULL, the | ||
| * function uses the computer specified in the szMachineName | ||
| * parameter to enumerate the names. | ||
| * @param szMachineName | ||
| * String that specifies the name of the computer that contains | ||
| * the counter and instance names that you want to enumerate. | ||
| * Include the leading slashes in the computer name, for example, | ||
| * \\computername. If the szDataSource parameter is NULL, you can | ||
| * set szMachineName to NULL to specify the local computer. | ||
| * @param szObjectName | ||
| * String that specifies the name of the object whose counter and | ||
| * instance names you want to enumerate. | ||
| * @param dwDetailLevel | ||
| * Detail level of the performance items to return. All items | ||
| * that are of the specified detail level or less will be | ||
| * returned. | ||
| * @return Returns a List with two elements. Index 0 contains a List of | ||
| * Strings of the counters for the object. Index 1 contains a List | ||
| * of Strings of the instances of the object. | ||
| */ | ||
| public static List<List<String>> PdhEnumObjectItems(String szDataSource, String szMachineName, String szObjectName, | ||
| int dwDetailLevel) { | ||
| int charToBytes = Boolean.getBoolean("w32.ascii") ? 1 : Native.WCHAR_SIZE; | ||
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| // Call once to get string lengths | ||
| DWORDByReference pcchCounterListLength = new DWORDByReference(new DWORD(0)); | ||
| DWORDByReference pcchInstanceListLength = new DWORDByReference(new DWORD(0)); | ||
| Pdh.INSTANCE.PdhEnumObjectItems(szDataSource, szMachineName, szObjectName, null, pcchCounterListLength, null, | ||
| pcchInstanceListLength, dwDetailLevel, 0); | ||
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| // Allocate memory and call again to populate strings | ||
| Memory mszCounterList = new Memory(pcchCounterListLength.getValue().intValue() * charToBytes); | ||
| Memory mszInstanceList = new Memory(pcchInstanceListLength.getValue().intValue() * charToBytes); | ||
| Pdh.INSTANCE.PdhEnumObjectItems(szDataSource, szMachineName, szObjectName, mszCounterList, | ||
| pcchCounterListLength, mszInstanceList, pcchInstanceListLength, dwDetailLevel, 0); | ||
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| // Fetch counters | ||
| List<String> counters = new LinkedList<>(); | ||
|
There was a problem hiding this comment. In another issue it was noted, that the LinkedList is not the best list to choose. I suggest to switch to ArrayList. There was a problem hiding this comment. Sure, I'll switch. I'm curious the logic, though? I thought LinkedList was faster for adding (particularly when the final length is unknown) and ArrayList for getting. |
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| int offset = 0; | ||
| while (offset < mszCounterList.size()) { | ||
| String s = null; | ||
| if (charToBytes == 1) { | ||
| s = mszCounterList.getString(offset); | ||
| } else { | ||
| s = mszCounterList.getWideString(offset); | ||
| } | ||
| // list ends with double null | ||
| if (s.isEmpty()) { | ||
| break; | ||
| } | ||
| counters.add(s); | ||
| offset += (s.length() + 1) * charToBytes; | ||
| } | ||
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| List<String> instances = new LinkedList<>(); | ||
| offset = 0; | ||
| while (offset < mszInstanceList.size()) { | ||
| String s = null; | ||
| if (charToBytes == 1) { | ||
| s = mszInstanceList.getString(offset); | ||
| } else { | ||
| s = mszInstanceList.getWideString(offset); | ||
| } | ||
| // list ends with double null | ||
| if (s.isEmpty()) { | ||
| break; | ||
| } | ||
| instances.add(s); | ||
| // Increment for string + null terminator | ||
| offset += (s.length() + 1) * charToBytes; | ||
| } | ||
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| List<List<String>> objectItems = new ArrayList<>(2); | ||
| objectItems.add(counters); | ||
| objectItems.add(instances); | ||
| return objectItems; | ||
| } | ||
| } | ||
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I would think about splitting this method - is it performance critical? If not, I think two method (one for the conters and one for the instances would be better), the List of List of String feels strange.
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I had that same thought. In my application I only am using the instance list anyway. The List of lists is a step up from my original implementation as an array of lists, though, so give me partial credit.