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package jdk.vm.ci.hotspot;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import jdk.vm.ci.meta.ResolvedJavaMethod;
import jdk.vm.ci.meta.ResolvedJavaType;
import jdk.vm.ci.meta.SpeculationLog.SpeculationReasonEncoding;

Implements a SpeculationReasonEncoding that produces a byte array. Data is added via a DataOutputStream. When producing the final byte array, if the total length of data exceeds the length of a SHA-1 digest and a SHA-1 digest algorithm is available, then a SHA-1 digest of the data is produced instead.
/** * Implements a {@link SpeculationReasonEncoding} that {@linkplain #getByteArray() produces} a byte * array. Data is added via a {@link DataOutputStream}. When producing the final byte array, if the * total length of data exceeds the length of a SHA-1 digest and a SHA-1 digest algorithm is * available, then a SHA-1 digest of the data is produced instead. */
final class HotSpotSpeculationEncoding extends ByteArrayOutputStream implements SpeculationReasonEncoding { private DataOutputStream dos = new DataOutputStream(this); private byte[] result; HotSpotSpeculationEncoding() { super(SHA1_LENGTH); } private void checkOpen() { if (result != null) { throw new IllegalArgumentException("Cannot update closed speculation encoding"); } } private static final int NULL_METHOD = -1; private static final int NULL_TYPE = -2; private static final int NULL_STRING = -3; @Override public void addByte(int value) { checkOpen(); try { dos.writeByte(value); } catch (IOException e) { throw new InternalError(e); } } @Override public void addShort(int value) { checkOpen(); try { dos.writeShort(value); } catch (IOException e) { throw new InternalError(e); } } @Override public void addMethod(ResolvedJavaMethod method) { if (!addNull(method, NULL_METHOD)) { checkOpen(); if (method instanceof HotSpotResolvedJavaMethodImpl) { try { dos.writeLong(((HotSpotResolvedJavaMethodImpl) method).getMetaspaceMethod()); } catch (IOException e) { throw new InternalError(e); } } else { throw new IllegalArgumentException("Cannot encode unsupported type " + method.getClass().getName() + ": " + method.format("%H.%n(%p)")); } } } @Override public void addType(ResolvedJavaType type) { if (!addNull(type, NULL_TYPE)) { checkOpen(); if (type instanceof HotSpotResolvedObjectTypeImpl) { try { dos.writeLong(((HotSpotResolvedObjectTypeImpl) type).getMetaspaceKlass()); } catch (IOException e) { throw new InternalError(e); } } else { throw new IllegalArgumentException("Cannot encode unsupported type " + type.getClass().getName() + ": " + type.toClassName()); } } } @Override public void addString(String value) { if (!addNull(value, NULL_STRING)) { checkOpen(); try { dos.writeChars(value); } catch (IOException e) { throw new InternalError(e); } } } @Override public void addInt(int value) { checkOpen(); try { dos.writeInt(value); } catch (IOException e) { throw new InternalError(e); } } @Override public void addLong(long value) { checkOpen(); try { dos.writeLong(value); } catch (IOException e) { throw new InternalError(e); } } private boolean addNull(Object o, int nullValue) { if (o == null) { addInt(nullValue); return true; } return false; }
Prototype SHA1 digest.
/** * Prototype SHA1 digest. */
private static final MessageDigest SHA1;
Cloning the prototype is quicker than calling MessageDigest.getInstance(String) every time.
/** * Cloning the prototype is quicker than calling {@link MessageDigest#getInstance(String)} every * time. */
private static final boolean SHA1_IS_CLONEABLE; private static final int SHA1_LENGTH; static { MessageDigest sha1 = null; boolean sha1IsCloneable = false; try { sha1 = MessageDigest.getInstance("SHA-1"); sha1.clone(); sha1IsCloneable = true; } catch (NoSuchAlgorithmException e) { // Should never happen given that SHA-1 is mandated in a // compliant Java platform implementation. However, be // conservative and fall back to not using a digest. } catch (CloneNotSupportedException e) { } SHA1 = sha1; SHA1_IS_CLONEABLE = sha1IsCloneable; SHA1_LENGTH = SHA1 == null ? 20 : SHA1.getDigestLength(); }
Gets the final encoded byte array and closes this encoding such that any further attempts to update it result in an IllegalArgumentException.
/** * Gets the final encoded byte array and closes this encoding such that any further attempts to * update it result in an {@link IllegalArgumentException}. */
byte[] getByteArray() { if (result == null) { if (SHA1 != null && count > SHA1_LENGTH) { try { MessageDigest md = SHA1_IS_CLONEABLE ? (MessageDigest) SHA1.clone() : MessageDigest.getInstance("SHA-1"); md.update(buf, 0, count); result = md.digest(); } catch (CloneNotSupportedException | NoSuchAlgorithmException e) { throw new InternalError(e); } } else { if (buf.length == count) { // No need to copy the byte array return buf; } result = Arrays.copyOf(buf, count); } dos = null; } return result; } }