// Map.Lookup require updates to the hasher, so a full Mutex lock (not a
// read-lock) is require around all Map operations if a shared
// hasher is accessed from multiple threads.
//
// If SetHasher is not called, the Map will create a private hasher at
// the first call to Insert.
func (m *Map) SetHasher(hasher Hasher) {
	m.hasher = hasher
}

// Delete removes the entry with the given key, if any.

 * <h3>Memory considerations</h3>
 * <p>
 * Hashes by default are stored in {@link ByteArrayBackedHashCode a byte array}.
 * For a 128-bit hash this results in 64 bytes of memory used for each {@code HashCode}.
 * This implementation also requires GC to track two separate objects (the {@code HashCode} object and its {@code byte[]}).
 * <p>
 * Because Gradle uses a lot of MD5 hashes, for 128-bit hashes we have a more efficient implementation.

        when:
        hasher.hash(zipEntry('META-INF/foo'))
        hasher.hash(zipEntry('META-INF/foo/MANIFEST.MF'))
        hasher.hash(zipEntry('META-INF/properties'))
        hasher.hash(zipEntry('META-INF/build.propertiesX'))
        hasher.hash(zipEntry('bar.properties'))
        hasher.hash(zipEntry('resources/foo.properties'))
        hasher.hash(zipEntry('foo'))
        hasher.hash(zipEntry('org/gradle/foo.class'))

    }

    def "delegate configuration is added to hasher"() {
        def configurationHasher = Mock(Hasher)
        delegate = Mock(ResourceHasher)

        when:
        filteredHasher.appendConfigurationToHasher(configurationHasher)

        then:
        1 * delegate.appendConfigurationToHasher(configurationHasher)
    }

Der Dieb kann also nicht versuchen, die gleichen Passwörter in einem anderen System zu verwenden (da viele Benutzer überall das gleiche Passwort verwenden, wäre dies gefährlich).

## `passlib` installieren

PassLib ist ein großartiges Python-Package, um Passwort-Hashes zu handhaben.

        val root = this@hashWithoutMessages
        val hasher = Hashing.newHasher()
        for (failure in sequence { visitFailures(root) }) {
            hasher.putString(failure.exceptionType.name)
            for (element in failure.stackTrace) {
                hasher.putString(element.toString())
            }
        }
        return hasher.hash()
    }

    private

	}
	if ctxt != nil {
		ctxts = append(ctxts, ctxt)
	}
	assert(len(ctxts) > 0)

	// Compute all hashes; hashes may differ across contexts due to different
	// unique IDs for Named types within the hasher.
	hashes := make([]string, len(ctxts))
	for i, ctxt := range ctxts {
		hashes[i] = ctxt.instanceHash(orig, targs)
	}

	// Record the result in all contexts.

	}
	if ctxt != nil {
		ctxts = append(ctxts, ctxt)
	}
	assert(len(ctxts) > 0)

	// Compute all hashes; hashes may differ across contexts due to different
	// unique IDs for Named types within the hasher.
	hashes := make([]string, len(ctxts))
	for i, ctxt := range ctxts {
		hashes[i] = ctxt.instanceHash(orig, targs)
	}

	// Record the result in all contexts.

If your database is stolen, the thief won't have your users' plaintext passwords, only the hashes.

So, the thief won't be able to try to use that password in another system (as many users use the same password everywhere, this would be dangerous).

## Install `passlib`

PassLib is a great Python package to handle password hashes.

It supports many secure hashing algorithms and utilities to work with them.

            hasher.putInt(bytes.length);
            hasher.putBytes(bytes);
        }

        @Override
        public void putBytes(byte[] bytes, int off, int len) {
            hasher.putInt(len);
            hasher.putBytes(bytes, off, len);
        }

        @Override
        public void putHash(HashCode hashCode) {
            hasher.putInt(hashCode.length());
            hasher.putHash(hashCode);