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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "compiled_function.h"
#include <vespa/vespalib/util/executor.h>
#include <condition_variable>
#include <atomic>
#include <mutex>
namespace vespalib::eval {
/**
* A compilation cache used to reduce application configuration cost
* by not having to compile equivalent expressions multiple times. The
* expression AST is used to produce a binary key that in turn is used
* to query the cache. The cache itself will not keep anything alive,
* but will let you find compiled functions that are currently in use
* by others.
**/
class CompileCache
{
private:
using Key = vespalib::string;
struct Result {
using SP = std::shared_ptr<Result>;
std::atomic<const CompiledFunction *> cf;
std::mutex lock;
std::condition_variable cond;
CompiledFunction::UP compiled_function;
Result() noexcept : cf(nullptr), lock(), cond(), compiled_function(nullptr) {}
};
struct Value {
size_t num_refs;
Result::SP result;
struct ctor_tag {};
Value(ctor_tag) : num_refs(1), result(std::make_shared<Result>()) {}
const CompiledFunction &wait_for_result();
const CompiledFunction &get() {
const CompiledFunction *ptr = result->cf.load(std::memory_order_acquire);
if (ptr == nullptr) {
return wait_for_result();
}
return *ptr;
}
};
using Map = std::map<Key,Value>;
static std::mutex _lock;
static Map _cached;
static uint64_t _executor_tag;
static std::vector<std::pair<uint64_t,std::shared_ptr<Executor>>> _executor_stack;
static void release(Map::iterator entry);
static uint64_t attach_executor(std::shared_ptr<Executor> executor);
static void detach_executor(uint64_t tag);
public:
class Token
{
private:
friend class CompileCache;
struct ctor_tag {};
CompileCache::Map::iterator _entry;
public:
Token(Token &&) = delete;
Token(const Token &) = delete;
Token &operator=(Token &&) = delete;
Token &operator=(const Token &) = delete;
using UP = std::unique_ptr<Token>;
explicit Token(CompileCache::Map::iterator entry, ctor_tag) : _entry(entry) {}
const CompiledFunction &get() const { return _entry->second.get(); }
~Token() { CompileCache::release(_entry); }
};
class ExecutorBinding {
private:
friend class CompileCache;
uint64_t _tag;
struct ctor_tag {};
public:
ExecutorBinding(ExecutorBinding &&) = delete;
ExecutorBinding(const ExecutorBinding &) = delete;
ExecutorBinding &operator=(ExecutorBinding &&) = delete;
ExecutorBinding &operator=(const ExecutorBinding &) = delete;
using UP = std::unique_ptr<ExecutorBinding>;
explicit ExecutorBinding(std::shared_ptr<Executor> executor, ctor_tag)
: _tag(attach_executor(std::move(executor))) {}
~ExecutorBinding() { detach_executor(_tag); }
};
static Token::UP compile(const Function &function, PassParams pass_params);
static void wait_pending();
static ExecutorBinding::UP bind(std::shared_ptr<Executor> executor) {
return std::make_unique<ExecutorBinding>(std::move(executor), ExecutorBinding::ctor_tag());
}
static size_t num_cached();
static size_t num_bound();
static size_t count_refs();
static size_t count_pending();
private:
struct CompileTask : public Executor::Task {
std::shared_ptr<Function const> function;
PassParams pass_params;
Result::SP result;
CompileTask(const Function &function_in, PassParams pass_params_in, Result::SP result_in)
: function(function_in.shared_from_this()), pass_params(pass_params_in), result(std::move(result_in)) {}
void run() override;
};
};
}
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