HADOOP-11506. Configuration variable expansion regex expensive for long values. (Gera Shegalov via gera)
(cherry picked from commit 644548f201)
Conflicts:
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java
This commit is contained in:
Gera Shegalov
parent
92ff524182
commit
3d36d4737c
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@ -192,6 +192,9 @@ Release 2.7.0 - UNRELEASED
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HADOOP-11188. hadoop-azure: automatically expand page blobs when they become
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full. (Eric Hanson via cnauroth)
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HADOOP-11506. Configuration variable expansion regex expensive for long
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values. (Gera Shegalov via gera)
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BUG FIXES
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HADOOP-11488. Difference in default connection timeout for S3A FS
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@ -844,25 +844,101 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
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resources.add(resource); // add to resources
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reloadConfiguration();
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}
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private static final Pattern VAR_PATTERN =
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Pattern.compile("\\$\\{[^\\}\\$\u0020]+\\}");
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private static final int MAX_SUBST = 20;
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private static final int SUB_START_IDX = 0;
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private static final int SUB_END_IDX = SUB_START_IDX + 1;
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/**
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* This is a manual implementation of the following regex
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* "\\$\\{[^\\}\\$\u0020]+\\}". It can be 15x more efficient than
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* a regex matcher as demonstrated by HADOOP-11506. This is noticeable with
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* Hadoop apps building on the assumption Configuration#get is an O(1)
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* hash table lookup, especially when the eval is a long string.
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*
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* @param eval a string that may contain variables requiring expansion.
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* @return a 2-element int array res such that
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* eval.substring(res[0], res[1]) is "var" for the left-most occurrence of
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* ${var} in eval. If no variable is found -1, -1 is returned.
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*/
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private static int[] findSubVariable(String eval) {
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int[] result = {-1, -1};
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int matchStart;
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int leftBrace;
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// scanning for a brace first because it's less frequent than $
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// that can occur in nested class names
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//
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match_loop:
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for (matchStart = 1, leftBrace = eval.indexOf('{', matchStart);
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// minimum left brace position (follows '$')
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leftBrace > 0
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// right brace of a smallest valid expression "${c}"
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&& leftBrace + "{c".length() < eval.length();
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leftBrace = eval.indexOf('{', matchStart)) {
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int matchedLen = 0;
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if (eval.charAt(leftBrace - 1) == '$') {
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int subStart = leftBrace + 1; // after '{'
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for (int i = subStart; i < eval.length(); i++) {
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switch (eval.charAt(i)) {
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case '}':
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if (matchedLen > 0) { // match
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result[SUB_START_IDX] = subStart;
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result[SUB_END_IDX] = subStart + matchedLen;
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break match_loop;
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}
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// fall through to skip 1 char
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case ' ':
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case '$':
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matchStart = i + 1;
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continue match_loop;
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default:
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matchedLen++;
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}
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}
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// scanned from "${" to the end of eval, and no reset via ' ', '$':
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// no match!
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break match_loop;
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} else {
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// not a start of a variable
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//
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matchStart = leftBrace + 1;
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}
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}
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return result;
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}
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/**
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* Attempts to repeatedly expand the value {@code expr} by replacing the
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* left-most substring of the form "${var}" in the following precedence order
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* <ol>
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* <li>by the value of the Java system property "var" if defined</li>
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* <li>by the value of the configuration key "var" if defined</li>
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* </ol>
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*
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* If var is unbounded the current state of expansion "prefix${var}suffix" is
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* returned.
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*
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* @param expr the literal value of a config key
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* @return null if expr is null, otherwise the value resulting from expanding
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* expr using the algorithm above.
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* @throws IllegalArgumentException when more than
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* {@link Configuration#MAX_SUBST} replacements are required
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*/
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private String substituteVars(String expr) {
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if (expr == null) {
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return null;
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}
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Matcher match = VAR_PATTERN.matcher("");
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String eval = expr;
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for(int s=0; s<MAX_SUBST; s++) {
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match.reset(eval);
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if (!match.find()) {
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for (int s = 0; s < MAX_SUBST; s++) {
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final int[] varBounds = findSubVariable(eval);
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if (varBounds[SUB_START_IDX] == -1) {
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return eval;
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}
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String var = match.group();
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var = var.substring(2, var.length()-1); // remove ${ .. }
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final String var = eval.substring(varBounds[SUB_START_IDX],
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varBounds[SUB_END_IDX]);
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String val = null;
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try {
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val = System.getProperty(var);
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@ -875,8 +951,12 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
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if (val == null) {
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return eval; // return literal ${var}: var is unbound
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}
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final int dollar = varBounds[SUB_START_IDX] - "${".length();
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final int afterRightBrace = varBounds[SUB_END_IDX] + "}".length();
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// substitute
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eval = eval.substring(0, match.start())+val+eval.substring(match.end());
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eval = eval.substring(0, dollar)
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+ val
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+ eval.substring(afterRightBrace);
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}
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throw new IllegalStateException("Variable substitution depth too large: "
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+ MAX_SUBST + " " + expr);
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@ -49,6 +49,8 @@ import org.apache.hadoop.fs.Path;
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import org.apache.hadoop.io.IOUtils;
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import org.apache.hadoop.net.NetUtils;
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import static org.apache.hadoop.util.PlatformName.IBM_JAVA;
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import static org.junit.Assert.fail;
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import org.codehaus.jackson.map.ObjectMapper;
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public class TestConfiguration extends TestCase {
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@ -1194,6 +1196,70 @@ public class TestConfiguration extends TestCase {
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}
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}
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public void testInvalidSubstitutation() {
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final Configuration configuration = new Configuration(false);
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// 2-var loops
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//
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final String key = "test.random.key";
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for (String keyExpression : Arrays.asList(
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"${" + key + "}",
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"foo${" + key + "}",
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"foo${" + key + "}bar",
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"${" + key + "}bar")) {
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configuration.set(key, keyExpression);
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checkSubDepthException(configuration, key);
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}
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//
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// 3-variable loops
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//
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final String expVal1 = "${test.var2}";
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String testVar1 = "test.var1";
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configuration.set(testVar1, expVal1);
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configuration.set("test.var2", "${test.var3}");
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configuration.set("test.var3", "${test.var1}");
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checkSubDepthException(configuration, testVar1);
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// 3-variable loop with non-empty value prefix/suffix
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//
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final String expVal2 = "foo2${test.var2}bar2";
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configuration.set(testVar1, expVal2);
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configuration.set("test.var2", "foo3${test.var3}bar3");
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configuration.set("test.var3", "foo1${test.var1}bar1");
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checkSubDepthException(configuration, testVar1);
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}
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private static void checkSubDepthException(Configuration configuration,
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String key) {
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try {
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configuration.get(key);
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fail("IllegalStateException depth too large not thrown");
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} catch (IllegalStateException e) {
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assertTrue("Unexpected exception text: " + e,
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e.getMessage().contains("substitution depth"));
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}
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}
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public void testIncompleteSubbing() {
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Configuration configuration = new Configuration(false);
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String key = "test.random.key";
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for (String keyExpression : Arrays.asList(
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"{}",
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"${}",
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"{" + key,
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"${" + key,
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"foo${" + key,
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"foo${" + key + "bar",
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"foo{" + key + "}bar",
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"${" + key + "bar")) {
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configuration.set(key, keyExpression);
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String value = configuration.get(key);
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assertTrue("Unexpected value " + value, value.equals(keyExpression));
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}
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}
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public void testGetClassByNameOrNull() throws Exception {
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Configuration config = new Configuration();
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Class<?> clazz = config.getClassByNameOrNull("java.lang.Object");
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