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 * Copyright (c) 2016, 2020, Oracle and/or its affiliates.
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 * Redistribution and use in source and binary forms, with or without modification, are
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 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of
 * conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided
 * with the distribution.
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 * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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package com.oracle.truffle.llvm.runtime.memory;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.llvm.runtime.LLVMLanguage;

Holds the (lazily allocated) stacks of all threads that are active in one particular LLVMContext.
/**
 * Holds the (lazily allocated) stacks of all threads that are active in one particular LLVMContext.
 */
public final class LLVMThreadingStack {
    // we are not able to clean up a thread local properly, so we are using a map instead
    private final Map<Thread, LLVMStack> threadMap;
    private final long stackSize;
    private final Thread mainThread;

    public LLVMThreadingStack(Thread mainTread, long stackSize) {
        this.mainThread = mainTread;
        this.stackSize = stackSize;
        this.threadMap = new ConcurrentHashMap<>();
    }

    public LLVMStack getStack() {
        LLVMStack s = getCurrentStack();
        if (s == null) {
            s = createNewStack();
        }
        return s;
    }

    @TruffleBoundary
    private LLVMStack getCurrentStack() {
        return threadMap.get(Thread.currentThread());
    }

    @TruffleBoundary
    private LLVMStack createNewStack() {
        LLVMStack s = new LLVMStack(stackSize, LLVMLanguage.getContext());
        Object previous = threadMap.putIfAbsent(Thread.currentThread(), s);
        assert previous == null;
        return s;
    }

    @TruffleBoundary
    public void freeStack(LLVMMemory memory, Thread thread) {
        /*
         * Do not free the stack of the main thread: Sulong#disposeThread runs before
         * Sulong#disposeContext, which needs to call destructors that need a SP.
         */
        if (mainThread != Thread.currentThread()) {
            free(memory, thread);
        }
    }

    @TruffleBoundary
    public void freeMainStack(LLVMMemory memory) {
        free(memory, mainThread);
    }

    private void free(LLVMMemory memory, Thread thread) {
        LLVMStack s = threadMap.remove(thread);
        if (s != null) {
            s.free(memory);
        }
    }
}