com.kenai.jffi.Library Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of cassandra-driver Show documentation
Show all versions of cassandra-driver Show documentation
Shaded version of DataStax Java Driver for Apache Cassandra
/*
* Copyright (C) 2008, 2009 Wayne Meissner
*
* This file is part of jffi.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*
* Alternatively, you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this work. If not, see > cache
= new ConcurrentHashMap>();
/** A lock used to serialize all dlopen/dlsym calls */
private static final Object lock = new Object();
/** Stores the last error returned by a dlopen or dlsym call */
private static final ThreadLocal lastError = new ThreadLocal();
/** A handle to the current process */
private static final class DefaultLibrary {
private static final Library INSTANCE = openLibrary(null, LAZY | GLOBAL);
}
/** Perform lazy binding. Only resolve symbols as needed */
public static final int LAZY = Foreign.RTLD_LAZY;
/** Resolve all symbols when loading the library */
public static final int NOW = Foreign.RTLD_NOW;
/** Symbols in this library are not made available to other libraries */
public static final int LOCAL = Foreign.RTLD_LOCAL;
/** All symbols in the library are made available to other libraries */
public static final int GLOBAL = Foreign.RTLD_GLOBAL;
/** The native dl/LoadLibrary handle */
private final long handle;
/** The name of this Library */
private final String name;
/** A handle to the foreign interface to keep it alive as long as this object is alive */
private final Foreign foreign;
/**
* Internal wrapper around dlopen.
*
* If the library open fails, then this stores the native error in a thread
* local variable for later retrieval.
*
* @param name The name of the library to open
* @param flags The flags to pass to dlopen
* @return The native handle for the opened library, or 0 if it failed to open.
*/
private static long dlopen(Foreign foreign, String name, int flags) {
try {
return foreign.dlopen(name, flags);
} catch (UnsatisfiedLinkError ex) {
lastError.set(ex.getMessage());
return 0L;
}
}
/**
* Gets a handle to the default library.
*
* @return A Library instance representing the default library.
*/
public static final Library getDefault() {
return DefaultLibrary.INSTANCE;
}
/**
* Gets a handle for the named library.
*
* @param name The name or path of the library to open.
* @param flags The library flags (e.g. LAZY, NOW, LOCAL, GLOBAL)
* @return A Library instance representing the named library, or
* null if the library could not be opened.
*/
public static final Library getCachedInstance(String name, int flags) {
if (name == null) {
return getDefault();
}
WeakReference ref = cache.get(name);
Library lib = ref != null ? ref.get() : null;
if (lib != null) {
return lib;
}
lib = openLibrary(name, flags);
if (lib == null) {
return null;
}
cache.put(name, new WeakReference(lib));
return lib;
}
/**
* Gets a handle for the named library.
*
* Note This will not cache the instance, nor will it return a cached
* instance. Only use when you really need a new handle for the library.
*
* @param name The name or path of the library to open.
* @param flags The library flags (e.g. LAZY, NOW, LOCAL, GLOBAL)
* @return A Library instance representing the named library, or
* null if the library cannot be opened.
*/
public static final Library openLibrary(String name, int flags) {
// dlopen on some OS does not like flags=0, so set to sensible defaults
if (flags == 0) {
flags = LAZY | LOCAL;
}
final Foreign foreign = Foreign.getInstance();
final long address = dlopen(foreign, name, flags);
return address != 0L ? new Library(foreign, name, address) : null;
}
private Library(Foreign foreign, String name, long address) {
this.foreign = foreign;
this.name = name;
this.handle = address;
}
/**
* Gets the address of a symbol within the Library.
*
* @param name The name of the symbol to locate.
* @return The address of the symbol within the current address space.
*/
public final long getSymbolAddress(String name) {
try {
return foreign.dlsym(handle, name);
} catch (UnsatisfiedLinkError ex) {
lastError.set(foreign.dlerror());
return 0;
}
}
/**
* Gets the current error string from dlopen/LoadLibrary.
*
* @return A String describing the last error.
*/
public static final String getLastError() {
String error = lastError.get();
return error != null ? error : "unknown";
}
@Override
protected void finalize() throws Throwable {
try {
if (handle != 0L) {
foreign.dlclose(handle);
}
} finally {
super.finalize();
}
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy