diff options
Diffstat (limited to 'vespajlib/src/main/java')
-rw-r--r-- | vespajlib/src/main/java/com/yahoo/io/NativeIO.java | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/io/NativeIO.java b/vespajlib/src/main/java/com/yahoo/io/NativeIO.java new file mode 100644 index 00000000000..bee43a8653e --- /dev/null +++ b/vespajlib/src/main/java/com/yahoo/io/NativeIO.java @@ -0,0 +1,87 @@ +package com.yahoo.io; + +import java.io.File; +import java.io.FileDescriptor; +import java.io.FileInputStream; +import java.io.FileNotFoundException; +import java.io.IOException; +import java.lang.reflect.Field; +import java.util.logging.Logger; + +import com.sun.jna.LastErrorException; +import com.sun.jna.Native; +import com.sun.jna.Platform; + +public class NativeIO { + private final Logger logger = Logger.getLogger(getClass().getName()); + private static final int POSIX_FADV_DONTNEED = 4; // See /usr/include/linux/fadvise.h + private static boolean initialized = false; + private static Throwable initError = null; + static { + try { + if (Platform.isLinux()) { + Native.register(Platform.C_LIBRARY_NAME); + initialized = true; + } + } catch (Throwable throwable) { + initError = throwable; + } + } + + private static final Field fieldFD = getField(FileDescriptor.class, "fd"); + + + private static native int posix_fadvise(int fd, long offset, long len, int flag) throws LastErrorException; + + public NativeIO() { + if (!initialized) { + logger.warning("native IO not possible due to " + getError().getMessage()); + } + } + + public boolean valid() { return initialized; } + public Throwable getError() { + if (initError != null) { + return initError; + } else { + return new RuntimeException("Platform is unsúpported. Only supported on linux."); + } + } + + public void dropFileFromCache(FileDescriptor fd) { + if (initialized) { + posix_fadvise(getNativeFD(fd), 0, 0, POSIX_FADV_DONTNEED); + } + } + + public void dropFileFromCache(File file) { + try { + dropFileFromCache(new FileInputStream(file).getFD()); + } catch (FileNotFoundException e) { + throw new RuntimeException(e); + } catch (IOException e) { + throw new RuntimeException(e); + } + } + + + private static Field getField(Class<?> clazz, String fieldName) { + Field field; + try { + field = clazz.getDeclaredField(fieldName); + } catch (NoSuchFieldException e) { + throw new RuntimeException(e); + } + field.setAccessible(true); + return field; + } + + private static int getNativeFD(FileDescriptor fd) { + try { + return fieldFD.getInt(fd); + } catch (IllegalAccessException e) { + throw new RuntimeException(e); + } + } + +} |