CodeContext.cc

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/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS code_contexts for details.
 */
 
#include "squid.h"
#include "base/CodeContext.h"
#include "debug/Stream.h"
 
class FadingCodeContext: public CodeContext
{
public:
    /* CodeContext API */
    ScopedId codeContextGist() const override { return gist; }
    std::ostream &detailCodeContext(std::ostream &os) const override { return os << gist; }
 
    ScopedId gist; 
};
 
static CodeContext::Pointer &
Instance()
{
    static const auto Instance = new CodeContext::Pointer(nullptr);
    return *Instance;
}
 
const CodeContext::Pointer &
CodeContext::Current()
{
    return Instance();
}
 
void
CodeContext::ForgetCurrent()
{
    static const RefCount<FadingCodeContext> fadingCodeContext = new FadingCodeContext();
    auto &current = Instance();
    assert(current);
    current->busyTime.pause();
    fadingCodeContext->gist = current->codeContextGist();
    current = fadingCodeContext;
}
 
void
CodeContext::Entering(const Pointer &codeCtx)
{
    auto &current = Instance();
    if (current)
        ForgetCurrent(); // ensure orderly closure of the old context
    current = codeCtx;
    codeCtx->busyTime.resume();
    debugs(1, 5, codeCtx->codeContextGist());
}
 
void
CodeContext::Leaving()
{
    ForgetCurrent();
    auto &current = Instance();
    debugs(1, 7, *current);
    current = nullptr;
}
 
void
CodeContext::Reset()
{
    if (Instance())
        Leaving();
}
 
void
CodeContext::Reset(const Pointer codeCtx)
{
    if (codeCtx == Current())
        return; // context has not actually changed
 
    if (!codeCtx)
        return Leaving();
 
    Entering(codeCtx);
}
 
std::ostream &
CurrentCodeContextDetail(std::ostream &os)
{
    if (const auto ctx = CodeContext::Current())
        ctx->detailCodeContext(os);
    return os;
}