Multi-threaded execution

src/main/java/org/genesys/geotools/CountryCLI.java

@@ -21,6 +21,11 @@ import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.OutputStreamWriter;
 import java.util.Arrays;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -85,48 +90,89 @@ public class CountryCLI {
 		CountryOfOriginServiceImpl countryOfOriginService = new CountryOfOriginServiceImpl();
 		countryOfOriginService.afterPropertiesSet();
 
+		// Thread pool with nThreads concurrent threads
+		int nThreads = 4;
+		ExecutorService threadPool = Executors.newFixedThreadPool(nThreads);
+
 		StopWatch stopWatch = new StopWatch();
 
-		String[] nextLine;
 		int lineCount = 0;
+		int submitted = 0;
 
 		long lastLogTime = 0;
 		stopWatch.start();
-		while ((nextLine = reader.readNext()) != null) {
-
-			lineCount++;
-			stopWatch.split();
-			long processingTimeSeconds = stopWatch.getSplitTime() / 1000;
-			if ((lineCount % 1000 == 0) || (lastLogTime != processingTimeSeconds && processingTimeSeconds % 10 == 0)) {
-				System.err.println("FYI, " + lineCount + " entries have been processed in " + processingTimeSeconds
-						+ " = " + (lineCount / processingTimeSeconds) + " lines/second");
-				countryOfOriginService.printCache();
-				lastLogTime = processingTimeSeconds;
-			}
 
-			String[] writeLine = Arrays.copyOf(nextLine, nextLine.length + 1);
+		String[][] inputLines = new String[nThreads][];
+		Future<?>[] futures = new Future<?>[nThreads];
 
-			try {
-				String origCty = nextLine[columnOrigCty].trim();
-				float longitude = Float.parseFloat(nextLine[columnLongitude].trim());
-				float latitude = Float.parseFloat(nextLine[columnLatitude].trim());
+		do {
+			// Reset
+			for (int i = nThreads - 1; i >= 0; i--) {
+				inputLines[i] = null;
+				futures[i] = null;
+				submitted = 0;
+			}
 
-				try {
-					String geoCountry = countryOfOriginService.getCountries(longitude, latitude, origCty,
-							ALLOWED_DISTANCE_MARGIN);
-					writeLine[writeLine.length - 1] = geoCountry;
+			// Submit
+			for (int i = nThreads - 1; i >= 0; i--) {
+				String[] nextLine = reader.readNext();
+				lineCount++;
+
+				stopWatch.split();
+				long processingTimeSeconds = stopWatch.getSplitTime() / 1000;
+				if ((lineCount % 1000 == 0)
+						|| (lastLogTime != processingTimeSeconds && processingTimeSeconds % 10 == 0)) {
+					System.err.println("FYI, " + lineCount + " entries have been processed in " + processingTimeSeconds
+							+ " = " + (lineCount / processingTimeSeconds) + " lines/second");
+					countryOfOriginService.printCache();
+					lastLogTime = processingTimeSeconds;
+				}
 
-					// TODO Use origCty?
+				if (nextLine == null)
+					break;
 
-				} catch (Exception e) {
-					writeLine[writeLine.length - 1] = e.getMessage();
+				inputLines[i] = nextLine;
+				submitted++;
+
+				futures[i] = threadPool.submit(new Callable<String>() {
+					@Override
+					public String call() throws Exception {
+						try {
+							String origCty = nextLine[columnOrigCty].trim();
+							float longitude = Float.parseFloat(nextLine[columnLongitude].trim());
+							float latitude = Float.parseFloat(nextLine[columnLatitude].trim());
+
+							try {
+								return countryOfOriginService.getCountries(longitude, latitude, origCty,
+										ALLOWED_DISTANCE_MARGIN);
+
+							} catch (Exception e) {
+								return e.getMessage();
+							}
+						} catch (Throwable e) {
+							return "ERROR: " + e.getMessage();
+						}
+					}
+				});
+			}
+
+			// Retrieve results
+			for (int i = nThreads - 1; i >= 0; i--) {
+				if (futures[i] == null)
+					break;
+				String result = null;
+				try {
+					result = (String) futures[i].get();
+				} catch (InterruptedException | ExecutionException e) {
+					e.printStackTrace();
+					result = e.getMessage();
 				}
-			} catch (Throwable e) {
-				writeLine[writeLine.length - 1] = "ERROR: " + e.getMessage();
+				String[] writeLine = Arrays.copyOf(inputLines[i], inputLines[i].length + 1);
+				writeLine[writeLine.length - 1] = result;
+				writer.writeNext(writeLine);
 			}
+		} while (submitted > 0);
 
-			writer.writeNext(writeLine);
-		}
 		stopWatch.stop();
 
 		writer.close();