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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "doctypename.h"
#include <vespa/vespalib/util/exceptions.h>
#include <vespa/vespalib/util/sequence.h>
#include <vespa/vespalib/stllike/string.h>
#include <map>
#include <vector>
namespace proton {
/**
* This template defines a mapping from a document type name to a shared pointer
* to the template argument type.
*/
template <typename T>
class HandlerMap {
private:
using HandlerSP = typename std::shared_ptr<T>;
using StdMap = std::map<DocTypeName, HandlerSP>;
StdMap _handlers;
public:
/**
* A snapshot of the currently registered handlers. This
* implementation simply takes a copy of all the shared pointers
* in the map to keep the handlers alive. However, the current
* abstraction allows as to make a snapshot based on bald pointers
* using event barriers to resolve visibility constraints in the
* future without changing the external API.
**/
class Snapshot : public vespalib::Sequence<T*>
{
private:
std::vector<HandlerSP> _handlers;
size_t _offset;
public:
Snapshot() : _handlers(), _offset(0) { }
Snapshot(const StdMap &map) : _handlers(), _offset(0) {
_handlers.reserve(map.size());
for (auto itr : map) {
_handlers.push_back(itr.second);
}
}
Snapshot(std::vector<HandlerSP> &&handlers) : _handlers(std::move(handlers)), _offset(0) {}
Snapshot(Snapshot &&) noexcept = default;
Snapshot & operator = (Snapshot &&) noexcept = default;
Snapshot(const Snapshot &) = delete;
Snapshot & operator = (const Snapshot &) = delete;
bool valid() const override { return (_offset < _handlers.size()); }
T *get() const override { return _handlers[_offset].get(); }
void next() override { ++_offset; }
};
/**
* Convenience typedefs.
*/
typedef typename StdMap::iterator iterator;
typedef typename StdMap::const_iterator const_iterator;
/**
* Constructs a new instance of this class.
*/
HandlerMap() = default;
/**
* Registers a new handler for the given document type. If another handler
* was already registered under the same type, this method will return a
* pointer to that handler.
*
* @param docType The document type to register a handler for.
* @param handler The handler to register.
* @return The replaced handler, if any.
*/
HandlerSP
putHandler(const DocTypeName &docTypeNameVer,
const HandlerSP &handler)
{
if ( ! handler) {
throw vespalib::IllegalArgumentException(vespalib::make_string(
"Handler is null for docType '%s'",
docTypeNameVer.toString().c_str()));
}
iterator it = _handlers.find(docTypeNameVer);
if (it == _handlers.end()) {
_handlers[docTypeNameVer] = handler;
return HandlerSP();
}
HandlerSP ret = it->second;
it->second = handler;
return ret;
}
/**
* Returns the handler for the given document type. If no handler was
* registered, this method returns an empty shared pointer.
*
* @param docType The document type whose handler to return.
* @return The registered handler, if any.
*/
HandlerSP
getHandler(const DocTypeName &docTypeNameVer) const
{
const_iterator it = _handlers.find(docTypeNameVer);
if (it != _handlers.end()) {
return it->second;
}
return HandlerSP();
}
/**
* Returns the handler for the given document type. If no handler was
* registered, this method returns a null pointer.
*
* @param docType The document type whose handler to return.
* @return The registered handler, if any.
*/
T *
getHandlerPtr(const DocTypeName &docTypeNameVer) const
{
const_iterator it = _handlers.find(docTypeNameVer);
return (it != _handlers.end()) ? it->second.get() : nullptr;
}
bool hasHandler(const HandlerSP &handler) const {
bool found = false;
for (const auto &kv : _handlers) {
if (handler == kv.second) {
found = true;
break;
}
}
return found;
}
/**
* Removes and returns the handler for the given document type. If no
* handler was registered, this method returns an empty shared pointer.
*
* @param docType The document type whose handler to remove.
* @return The removed handler, if any.
*/
HandlerSP
removeHandler(const DocTypeName &docTypeNameVer)
{
iterator it = _handlers.find(docTypeNameVer);
if (it == _handlers.end()) {
return HandlerSP();
}
HandlerSP ret = it->second;
_handlers.erase(it);
return ret;
}
/**
* Clear all handlers.
*/
void clear() { _handlers.clear(); }
/**
* Create a snapshot of the handlers currently contained in this
* map and return it as a sequence. The returned sequence will
* ensure that all object pointers stay valid until it is deleted.
*
* @return handler sequence
**/
Snapshot snapshot() const { return Snapshot(_handlers); }
// we want to use snapshots rather than direct iteration to reduce locking;
// the below functions should be deprecated when possible.
iterator begin() { return _handlers.begin(); }
const_iterator begin() const { return _handlers.begin(); }
iterator end() { return _handlers.end(); }
const_iterator end() const { return _handlers.end(); }
size_t size() const { return _handlers.size(); }
};
} // namespace proton
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