Package com.mastfrog.util.streams.stdio

Class ThreadMappedStdIO

java.lang.Object
com.mastfrog.util.streams.stdio.ThreadMappedStdIO
public final class ThreadMappedStdIO extends Object
Allows System.out and System.err to be replaced just for a single thread, while leaving them alone for the rest of the system.

Note, this is neessarily imperfect - if some other code replaces Syetem.out with something else, we do not detect that situation (it would be impossible to know what to do anyway - maybe the replacement wraps our output, maybe it doesn't) - so this code assumes it is the only thing in the system fiddling with the identity of the system stdout.

System.out and System.err will be restored fully when the last concurrent thread exits a closure that replaced either, so this class is zero-impact when not actively in use. Note: There are synchronized blocks on initiating and exiting, so if many threads are contending to replace stdio, liveness issues are possible.

Reentrancy is supported, so a thread may replace stdout and stderr, then do so again, and state will be restored correctly as each caller exits its closure.

Basically, the issue is that Antlr has calls to println baked into it, parsers and lexers by default attach listeners that do so as well, and catching every case where one might not have them removed is difficult. The output is more usefully routed to the output window anyway, so getting it out of the console output is handy.

Author:
Tim Boudreau

  • Method Summary

    Modifier and Type
    Method
    Description
    static void
    blackhole(ThrowingRunnable toRun)
    Discard any attempts at writing to stdout or stderr during the closure of the passed runnable, while not interfering with output from other threads.
    static <T> T
    blackhole(ThrowingSupplier<T> toRun)
    Discard any attempts at writing to stdout or stderr during the closure of the passed supplier, while not interfering with output from other threads.
    static void
    blackhole(Runnable toRun)
    Discard any attempts at writing to stdout or stderr during the closure of the passed runnable, while not interfering with output from other threads.
    static <T> T
    blackholeNonThrowing(Supplier<T> toRun)
    Discard any attempts at writing to stdout or stderr during the closure of the passed supplier, while not interfering with output from other threads.
    static void
    bypass(Runnable r)
    If any alternate stdout or stderr is set for the current thread, bypass that and use the original for one runnable; this is needed in cases where you are patching or subclassing in a library that is sloppy with stdout, but you have things you legitimately need to log, and want to be sure that a console logger logs to the right place.
    static void
    enter(PrintStream output, ThrowingRunnable toRun)
    Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingRunnable.
    static <T> T
    enter(PrintStream output, ThrowingSupplier<T> toRun)
    Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingSupplier.
    static void
    enter(PrintStream output, PrintStream error, ThrowingRunnable toRun)
    Replace the standard output and error with the passed streams, for the current thread, for the duration of the closure of the passed ThrowingRunnable.
    static <T> T
    enter(PrintStream output, PrintStream error, ThrowingSupplier<T> toRun)
    Replace the standard output and error with the passed streams, for the current thread, for the duration of the closure of the passed ThrowingSupplier.
    static void
    enterNonThrowing(PrintStream output, PrintStream error, Runnable toRun)
    Replace the standard output and error with the passed streams, for the current thread, for the duration of the closure of the passed ThrowingRunnable.
    static <T> T
    enterNonThrowing(PrintStream stdout, PrintStream stderr, Supplier<T> toRun)
    Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingSupplier.
    static void
    enterNonThrowing(PrintStream output, Runnable toRun)
    Replace the standard output and error with the passed stream, for the current thread, for the duration of the closure of the passed Runnable.
    static <T> T
    enterNonThrowing(PrintStream output, Supplier<T> toRun)
    Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingSupplier.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • bypass

      public static void bypass(Runnable r)
      If any alternate stdout or stderr is set for the current thread, bypass that and use the original for one runnable; this is needed in cases where you are patching or subclassing in a library that is sloppy with stdout, but you have things you legitimately need to log, and want to be sure that a console logger logs to the right place.
      Parameters:
      r - A runnable

    • blackholeNonThrowing

      public static <T> T blackholeNonThrowing(Supplier<T> toRun)
      Discard any attempts at writing to stdout or stderr during the closure of the passed supplier, while not interfering with output from other threads.
      Type Parameters:
      T - The return type
      Parameters:
      toRun - A supplier
      Returns:
      The value returned by the supplier

    • blackhole

      public static void blackhole(Runnable toRun)
      Discard any attempts at writing to stdout or stderr during the closure of the passed runnable, while not interfering with output from other threads.
      Parameters:
      toRun - A runnable

    • blackhole

      public static void blackhole(ThrowingRunnable toRun) throws Exception
      Discard any attempts at writing to stdout or stderr during the closure of the passed runnable, while not interfering with output from other threads.
      Parameters:
      toRun - A runnable
      Throws:
      Exception

    • blackhole

      public static <T> T blackhole(ThrowingSupplier<T> toRun) throws Exception
      Discard any attempts at writing to stdout or stderr during the closure of the passed supplier, while not interfering with output from other threads.
      Type Parameters:
      T - The return type
      Parameters:
      toRun - A supplier
      Returns:
      The value returned by the supplier
      Throws:
      Exception

    • enter

      public static <T> T enter(PrintStream output, ThrowingSupplier<T> toRun) throws Exception
      Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingSupplier.
      Type Parameters:
      T - The return type
      Parameters:
      output - The print stream to output to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Returns:
      The result of the supplier
      Throws:
      Exception - If something goes wrong

    • enterNonThrowing

      public static <T> T enterNonThrowing(PrintStream output, Supplier<T> toRun)
      Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingSupplier.
      Type Parameters:
      T - The return type
      Parameters:
      output - The print stream to output to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Returns:
      The result of the supplier
      Throws:
      Exception - If something goes wrong

    • enterNonThrowing

      public static <T> T enterNonThrowing(PrintStream stdout, PrintStream stderr, Supplier<T> toRun)
      Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingSupplier.
      Type Parameters:
      T - The return type
      Parameters:
      stdout - The print stream to output to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Returns:
      The result of the supplier
      Throws:
      Exception - If something goes wrong

    • enter

      public static void enter(PrintStream output, ThrowingRunnable toRun) throws Exception
      Replace the standard output and error with a single stream, for the current thread, for the duration of the closure of the passed ThrowingRunnable.
      Parameters:
      output - The print stream to output to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Throws:
      Exception - If something goes wrong

    • enter

      public static void enter(PrintStream output, PrintStream error, ThrowingRunnable toRun) throws Exception
      Replace the standard output and error with the passed streams, for the current thread, for the duration of the closure of the passed ThrowingRunnable.
      Parameters:
      output - The print stream to output stdout to instead of the system one
      error - The print stream to output stderr to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Throws:
      Exception - If something goes wrong

    • enterNonThrowing

      public static void enterNonThrowing(PrintStream output, PrintStream error, Runnable toRun)
      Replace the standard output and error with the passed streams, for the current thread, for the duration of the closure of the passed ThrowingRunnable.
      Parameters:
      output - The print stream to output stdout to instead of the system one
      error - The print stream to output stderr to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Throws:
      Exception - If something goes wrong

    • enterNonThrowing

      public static void enterNonThrowing(PrintStream output, Runnable toRun)
      Replace the standard output and error with the passed stream, for the current thread, for the duration of the closure of the passed Runnable.
      Parameters:
      output - The print stream to output stdout to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Throws:
      Exception - If something goes wrong

    • enter

      public static <T> T enter(PrintStream output, PrintStream error, ThrowingSupplier<T> toRun) throws Exception
      Replace the standard output and error with the passed streams, for the current thread, for the duration of the closure of the passed ThrowingSupplier.
      Type Parameters:
      T - The return type
      Parameters:
      output - The print stream to output stdout to instead of the system one
      error - The print stream to output stderr to instead of the system one
      toRun - The code to run with that set as the stdout and stderr
      Returns:
      The result of the supplier
      Throws:
      Exception - If something goes wrong