85 lines
2.1 KiB
Java
85 lines
2.1 KiB
Java
package dev.toad.ffi;
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import java.lang.ref.Cleaner;
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import java.util.Arrays;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.Optional;
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/**
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* A native pointer into the memory region shared between toadlib and the jvm
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*
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* Most notably, this ties into all `_Ref` classes' `close()` implementations;
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* when the toad runtime closes these objects, their pointers are `release()`d.
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*
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* Attempts to store and then use one of these Ref objects will throw a
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* `Ptr.ExpiredError`, as control has since been yielded to Rust code and the
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* address we had may have been invalidated by it.
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*/
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public class Ptr {
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private static final HashSet<Long> validAddresses = new HashSet<>();
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protected final long addr;
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private final String clazz;
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private final String trace;
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/**
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* Associate a class instance with a native pointer
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*/
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public static Ptr register(Class c, long addr) {
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var trace = Thread.currentThread().getStackTrace();
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var traceStr = Arrays
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.asList(trace)
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.stream()
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.skip(2)
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.map(StackTraceElement::toString)
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.reduce("", (s, tr) -> s == "" ? tr : s + "\n\t" + tr);
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Ptr.validAddresses.add(addr);
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return new Ptr(addr, c.toString(), traceStr);
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}
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private Ptr(long addr, String clazz, String trace) {
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this.clazz = clazz;
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this.addr = addr;
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this.trace = trace;
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}
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/**
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* Invokes the cleaning action on the object associated with an address
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*/
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public void release() {
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Ptr.validAddresses.remove(this.addr);
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}
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/**
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* Throw `ExpiredError` if object has been leaked
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* outside of its appropriate context.
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*/
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public void ensureValid() {
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if (!Ptr.validAddresses.contains(this.addr)) {
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throw new ExpiredError(this);
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}
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}
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public long addr() {
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this.ensureValid();
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return this.addr;
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}
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public static class ExpiredError extends Error {
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private static final String fmt =
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"Instance of %s may not be stored by user code.\n" +
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"Object was registered by:\n" +
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">>>>>>\n" +
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"%s\n" +
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"<<<<<<\n";
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ExpiredError(Ptr ptr) {
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super(String.format(fmt, ptr.clazz, ptr.trace));
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}
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}
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}
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