mass rename and rebranding from xwt to ibex - fixed to use ixt files

[org.ibex.core.git] / src / org / ibex / util / CachedInputStream.java

diff --git a/src/org/ibex/util/CachedInputStream.java b/src/org/ibex/util/CachedInputStream.java
new file mode 100644 (file)
index 0000000..a712f84
--- /dev/null
+++ b/src/org/ibex/util/CachedInputStream.java
@@ -0,0 +1,88 @@
+// Copyright (C) 2003 Adam Megacz <adam@ibex.org> all rights reserved.
+//
+// You may modify, copy, and redistribute this code under the terms of
+// the GNU Library Public License version 2.1, with the exception of
+// the portion of clause 6a after the semicolon (aka the "obnoxious
+// relink clause")
+
+package org.ibex.util;
+import java.io.*;
+
+// FEATURE: don't use a byte[] if we have a diskCache file
+/**
+ *  Wraps around an InputStream, caching the stream in a byte[] as it
+ *  is read and permitting multiple simultaneous readers
+ */
+public class CachedInputStream {
+
+    boolean filling = false;               ///< true iff some thread is blocked on us waiting for input
+    boolean eof = false;                   ///< true iff end of stream has been reached
+    byte[] cache = new byte[1024 * 128];
+    int size = 0;
+    final InputStream is;
+    File diskCache;
+
+    public CachedInputStream(InputStream is) { this(is, null); }
+    public CachedInputStream(InputStream is, File diskCache) {
+        this.is = is;
+        this.diskCache = diskCache;
+    }
+    public InputStream getInputStream() throws IOException {
+        if (diskCache != null && diskCache.exists()) return new FileInputStream(diskCache);
+        return new SubStream();
+    }
+
+    public void grow(int newLength) {
+        if (newLength < cache.length) return;
+        byte[] newCache = new byte[cache.length + 2 * (newLength - cache.length)];
+        System.arraycopy(cache, 0, newCache, 0, size);
+        cache = newCache;
+    }
+
+    synchronized void fillCache(int howMuch) throws IOException {
+        if (filling) { try { wait(); } catch (InterruptedException e) { }; return; }
+        filling = true;
+        grow(size + howMuch);
+        int ret = is.read(cache, size, howMuch);
+        if (ret == -1) {
+            eof = true;
+            // FIXME: probably a race here
+            if (diskCache != null && !diskCache.exists())
+                try {
+                    File cacheFile = new File(diskCache + ".incomplete");
+                    FileOutputStream cacheFileStream = new FileOutputStream(cacheFile);
+                    cacheFileStream.write(cache, 0, size);
+                    cacheFileStream.close();
+                    cacheFile.renameTo(diskCache);
+                } catch (IOException e) {
+                    Log.info(this, "exception thrown while writing disk cache");
+                    Log.info(this, e);
+                }
+        }
+        else size += ret;
+        filling = false;
+        notifyAll();
+    }
+
+    private class SubStream extends InputStream implements KnownLength {
+        int pos = 0;
+        public int available() { return Math.max(0, size - pos); }
+        public long skip(long n) throws IOException { pos += (int)n; return n; }     // FEATURE: don't skip past EOF
+        public int getLength() { return eof ? size : is instanceof KnownLength ? ((KnownLength)is).getLength() : 0; }
+        public int read() throws IOException {                                       // FEATURE: be smarter here
+            byte[] b = new byte[1];
+            int ret = read(b, 0, 1);
+            return ret == -1 ? -1 : b[0]&0xff;
+        }
+        public int read(byte[] b, int off, int len) throws IOException {
+            synchronized(CachedInputStream.this) {
+                while (pos >= size && !eof) fillCache(pos + len - size);
+                if (eof && pos == size) return -1;
+                int count = Math.min(size - pos, len);
+                System.arraycopy(cache, pos, b, off, count);
+                pos += count;
+                return count;
+            }
+        }
+    }
+}