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try to add a better localhost resolver. See issue riemann#44
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91 changes: 91 additions & 0 deletions
91
src/main/java/com/aphyr/riemann/client/LocalhostResolver.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,91 @@ | ||
| package com.aphyr.riemann.client; | ||
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| import java.net.UnknownHostException; | ||
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| /** | ||
| * A "Smarter" localhost resolver | ||
| * see issue: https://github.com/aphyr/riemann-java-client/issues/44 | ||
| * Trying to avoid a lot of calls to java.net.InetAddress.getLocalHost() | ||
| * which under AWS trigger DNS resolving and have relatively high latency *per event* | ||
| * usually, the hostname doesn't change so often to warrant a real query. | ||
| * | ||
| * A real call to java.net.InetAddress.getLocalHost().getHostName() | ||
| * is made only if: | ||
| * 1) the refresh interval has passed (=result is stale) | ||
| * AND | ||
| * 2) no env vars that identify the hostname are found | ||
| */ | ||
| public class LocalhostResolver { | ||
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| // default hostname env var names on Win/Nix | ||
| public static final String COMPUTERNAME = "COMPUTERNAME"; // Windows | ||
| public static final String HOSTNAME = "HOSTNAME"; // Nix | ||
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| // how often should we refresh the cached hostname | ||
| public static long RefreshIntervalMillis = 60 * 1000; | ||
| // enables setting a custom env var used for resolving | ||
| public static String CustomEnvVarName = null; | ||
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| // cached hostname result | ||
| private static String hostname; | ||
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| // update (refresh) time management | ||
| private static long lastUpdate = 0; | ||
| private static long lastNetUpdate = 0; | ||
| public static long getLastUpdateTime() { return lastUpdate; } | ||
| public static long getLastNetUpdateTime() { return lastNetUpdate; } | ||
| public static void resetUpdateTimes() { | ||
| lastUpdate = 0; | ||
| lastNetUpdate = 0; | ||
| } | ||
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| /** | ||
| * get resolved hostname. | ||
| * encapsulates all lookup and caching logic. | ||
| * | ||
| * @return the hostname | ||
| */ | ||
| public static String getResolvedHostname() { | ||
| long now = System.currentTimeMillis(); | ||
| if(now - RefreshIntervalMillis > lastUpdate) { | ||
| refreshResolve(); | ||
| } | ||
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| return hostname; | ||
| } | ||
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| /** | ||
| * forces a new resolve even if refresh interval has not passed yet | ||
| */ | ||
| public static void refreshResolve() { | ||
| try { | ||
| hostname = resolveByEnv(); | ||
| if(hostname == null || hostname.isEmpty()) { | ||
| hostname = java.net.InetAddress.getLocalHost().getHostName(); | ||
| lastNetUpdate = System.currentTimeMillis(); | ||
| } | ||
| } catch (UnknownHostException e) { | ||
| //e.printStackTrace(); | ||
| } | ||
| finally { | ||
| lastUpdate = System.currentTimeMillis(); | ||
| } | ||
| } | ||
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| /** | ||
| * try to resolve the hostname by env vars | ||
| * | ||
| * @return | ||
| */ | ||
| private static String resolveByEnv() { | ||
| if(CustomEnvVarName != null) { | ||
| return System.getenv(CustomEnvVarName); | ||
| } | ||
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| if(System.getProperty("os.name").startsWith("Windows")) { | ||
| return System.getenv(COMPUTERNAME); | ||
| } | ||
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| return System.getenv(HOSTNAME); | ||
| } | ||
| } |
146 changes: 146 additions & 0 deletions
146
src/test/java/riemann/java/client/tests/LocalhostResolveTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,146 @@ | ||
| package riemann.java.client.tests; | ||
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| import com.aphyr.riemann.client.LocalhostResolver; | ||
| import junit.framework.Assert; | ||
| import org.junit.Before; | ||
| import org.junit.BeforeClass; | ||
| import org.junit.Test; | ||
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| import java.lang.reflect.Field; | ||
| import java.net.UnknownHostException; | ||
| import java.util.Collections; | ||
| import java.util.HashMap; | ||
| import java.util.Map; | ||
|
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| public class LocalhostResolveTest { | ||
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| protected Map<String, String> env = new HashMap<String, String>(); | ||
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| protected static final String OS_NAME_PROP = "os.name"; | ||
| protected static final String ExpectedWinHostname = "LocalHostResolverTestWin"; | ||
| protected static final String ExpectedNixHostname = "LocalHostResolverTestNix"; | ||
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| @BeforeClass | ||
| public static void oneTimeSetUp() { | ||
| LocalhostResolver.RefreshIntervalMillis = 1000; | ||
| } | ||
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| @Before | ||
| public void setup() { | ||
| env = new HashMap<String, String>(System.getenv()); | ||
| env.put(LocalhostResolver.HOSTNAME, ExpectedNixHostname); | ||
| env.put(LocalhostResolver.COMPUTERNAME, ExpectedWinHostname); | ||
| setEnv(env); | ||
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| LocalhostResolver.CustomEnvVarName = null; | ||
| LocalhostResolver.resetUpdateTimes(); | ||
| Assert.assertEquals(0, LocalhostResolver.getLastUpdateTime()); | ||
| Assert.assertEquals(0, LocalhostResolver.getLastNetUpdateTime()); | ||
| } | ||
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| @Test | ||
| public void testUpdateInterval() { | ||
| Assert.assertEquals(0, LocalhostResolver.getLastUpdateTime()); | ||
| String hostname = LocalhostResolver.getResolvedHostname(); | ||
| long lastUpdateTime = LocalhostResolver.getLastUpdateTime(); | ||
| Assert.assertNotNull(hostname); | ||
| try { | ||
| Thread.sleep(1500); | ||
| } catch (InterruptedException e) { | ||
| e.printStackTrace(); | ||
| } | ||
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| Assert.assertNotSame(lastUpdateTime, LocalhostResolver.getLastUpdateTime()); | ||
| } | ||
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| @Test | ||
| public void testNoEnvVars() throws UnknownHostException { | ||
| env.remove(LocalhostResolver.HOSTNAME); | ||
| env.remove(LocalhostResolver.COMPUTERNAME); | ||
| setEnv(env); | ||
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| String hostname = LocalhostResolver.getResolvedHostname(); | ||
| Assert.assertNotNull(hostname); | ||
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| try { | ||
| Thread.sleep(1500); | ||
| } catch (InterruptedException e) { | ||
| e.printStackTrace(); | ||
| } | ||
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| // ensure queried hostname without env vars | ||
| Assert.assertEquals(LocalhostResolver.getLastUpdateTime(), LocalhostResolver.getLastNetUpdateTime()); | ||
| Assert.assertEquals(java.net.InetAddress.getLocalHost().getHostName(), hostname); | ||
| } | ||
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| @Test | ||
| public void testEnvVarWindows() { | ||
| System.getProperties().put(OS_NAME_PROP, "Windows7"); | ||
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| String hostname = LocalhostResolver.getResolvedHostname(); | ||
| Assert.assertEquals(ExpectedWinHostname, hostname); | ||
| Assert.assertEquals(0, LocalhostResolver.getLastNetUpdateTime()); | ||
| } | ||
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| @Test | ||
| public void testEnvVarNix() { | ||
| System.getProperties().put(OS_NAME_PROP, "Linux"); | ||
| String hostname = LocalhostResolver.getResolvedHostname(); | ||
| Assert.assertEquals(ExpectedNixHostname, hostname); | ||
| Assert.assertEquals(0, LocalhostResolver.getLastNetUpdateTime()); | ||
| } | ||
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| @Test | ||
| public void testCustomEnvVar() { | ||
| final String customHostnameEnvVar = "AWS_HOST"; | ||
| final String customHostname = "EC2-LocalHostResolverTest"; | ||
| env.put(customHostnameEnvVar, customHostname); | ||
| setEnv(env); | ||
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| LocalhostResolver.CustomEnvVarName = customHostnameEnvVar; | ||
| String hostname = LocalhostResolver.getResolvedHostname(); | ||
| Assert.assertEquals(customHostname, hostname); | ||
| Assert.assertEquals(0, LocalhostResolver.getLastNetUpdateTime()); | ||
| } | ||
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| /** | ||
| * evil hack for testing (only!) with env var in-memory modification | ||
| * see: http://stackoverflow.com/a/7201825/1469004 | ||
| * | ||
| * @param newEnv - to set in memory | ||
| */ | ||
| protected static void setEnv(Map<String, String> newEnv) { | ||
| try { | ||
| Class<?> processEnvironmentClass = Class.forName("java.lang.ProcessEnvironment"); | ||
| Field theEnvironmentField = processEnvironmentClass.getDeclaredField("theEnvironment"); | ||
| theEnvironmentField.setAccessible(true); | ||
| Map<String, String> env = (Map<String, String>) theEnvironmentField.get(null); | ||
| env.putAll(newEnv); | ||
| Field theCaseInsensitiveEnvironmentField = processEnvironmentClass.getDeclaredField("theCaseInsensitiveEnvironment"); | ||
| theCaseInsensitiveEnvironmentField.setAccessible(true); | ||
| Map<String, String> cienv = (Map<String, String>) theCaseInsensitiveEnvironmentField.get(null); | ||
| cienv.putAll(newEnv); | ||
| } | ||
| catch (NoSuchFieldException e) { | ||
| try { | ||
| Class[] classes = Collections.class.getDeclaredClasses(); | ||
| Map<String, String> env = System.getenv(); | ||
| for(Class cl : classes) { | ||
| if("java.util.Collections$UnmodifiableMap".equals(cl.getName())) { | ||
| Field field = cl.getDeclaredField("m"); | ||
| field.setAccessible(true); | ||
| Object obj = field.get(env); | ||
| Map<String, String> map = (Map<String, String>) obj; | ||
| map.clear(); | ||
| map.putAll(newEnv); | ||
| } | ||
| } | ||
| } catch (Exception e2) { | ||
| e2.printStackTrace(); | ||
| } | ||
| } catch (Exception e1) { | ||
| e1.printStackTrace(); | ||
| } | ||
| } | ||
| } |