package stirling.software.SPDF.utils; import java.io.BufferedReader; import java.util.concurrent.ConcurrentHashMap; import java.io.IOException; import java.io.InputStreamReader; import java.nio.charset.StandardCharsets; import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.concurrent.Semaphore; public class ProcessExecutor { public enum Processes { LIBRE_OFFICE, OCR_MY_PDF } private static final Map instances = new ConcurrentHashMap<>(); private final Semaphore semaphore; private ProcessExecutor(int semaphoreLimit) { this.semaphore = new Semaphore(semaphoreLimit); } public static ProcessExecutor getInstance(Processes processType) { return instances.computeIfAbsent(processType, key -> { int semaphoreLimit = switch (key) { case LIBRE_OFFICE -> 1; case OCR_MY_PDF -> 2; }; return new ProcessExecutor(semaphoreLimit); }); } public int runCommandWithOutputHandling(List command) throws IOException, InterruptedException { int exitCode = 1; semaphore.acquire(); try { System.out.print("Running command: " + String.join(" ", command)); ProcessBuilder processBuilder = new ProcessBuilder(command); Process process = processBuilder.start(); // Read the error stream and standard output stream concurrently List errorLines = new ArrayList<>(); List outputLines = new ArrayList<>(); Thread errorReaderThread = new Thread(() -> { try (BufferedReader errorReader = new BufferedReader(new InputStreamReader(process.getErrorStream(), StandardCharsets.UTF_8))) { String line; while ((line = errorReader.readLine()) != null) { errorLines.add(line); } } catch (IOException e) { e.printStackTrace(); } }); Thread outputReaderThread = new Thread(() -> { try (BufferedReader outputReader = new BufferedReader(new InputStreamReader(process.getInputStream(), StandardCharsets.UTF_8))) { String line; while ((line = outputReader.readLine()) != null) { outputLines.add(line); } } catch (IOException e) { e.printStackTrace(); } }); errorReaderThread.start(); outputReaderThread.start(); // Wait for the conversion process to complete exitCode = process.waitFor(); // Wait for the reader threads to finish errorReaderThread.join(); outputReaderThread.join(); if (outputLines.size() > 0) { String outputMessage = String.join("\n", outputLines); System.out.println("Command output:\n" + outputMessage); } if (errorLines.size() > 0) { String errorMessage = String.join("\n", errorLines); System.out.println("Command error output:\n" + errorMessage); if (exitCode != 0) { throw new IOException("Command process failed with exit code " + exitCode + ". Error message: " + errorMessage); } } } finally { semaphore.release(); } return exitCode; } }