APICache.cpp
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#include "hueplusplus/APICache.h"
/**
\file BaseHttpHandler.cpp
Copyright Notice\n
Copyright (C) 2020 Jan Rogall - developer\n
Copyright (C) 2020 Moritz Wirger - developer\n
This file is part of hueplusplus.
hueplusplus is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
hueplusplus is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with hueplusplus. If not, see <http://www.gnu.org/licenses/>.
**/
#include "hueplusplus/HueExceptionMacro.h"
namespace hueplusplus
{
APICache::APICache(
std::shared_ptr<APICache> baseCache, const std::string& subEntry, std::chrono::steady_clock::duration refresh)
: base(baseCache),
path(subEntry),
commands(baseCache->commands),
refreshDuration(refresh),
lastRefresh(baseCache->lastRefresh)
{ }
APICache::APICache(const std::string& path, const HueCommandAPI& commands, std::chrono::steady_clock::duration refresh,
const nlohmann::json& initial)
: path(path),
commands(commands),
refreshDuration(refresh),
lastRefresh(initial.is_null() ? std::chrono::steady_clock::time_point() : std::chrono::steady_clock::now()),
value(initial)
{ }
void APICache::refresh()
{
// Only refresh part of the cache, because that is more efficient
if (base && base->needsRefresh())
{
base->refresh();
}
else
{
nlohmann::json result = commands.GETRequest(getRequestPath(), nlohmann::json::object(), CURRENT_FILE_INFO);
lastRefresh = std::chrono::steady_clock::now();
if (base)
{
base->value[path] = std::move(result);
}
else
{
value = std::move(result);
}
}
}
nlohmann::json& APICache::getValue()
{
if (needsRefresh())
{
refresh();
}
if (base)
{
// Do not call getValue here, because that could cause another refresh
// if base has refresh duration 0
nlohmann::json& baseState = base->value;
auto pos = baseState.find(path);
if (pos != baseState.end())
{
return *pos;
}
else
{
throw HueException(CURRENT_FILE_INFO, "Child path not present in base cache");
}
}
else
{
return value;
}
}
const nlohmann::json& APICache::getValue() const
{
if (base)
{
// Make const reference to not refresh
const APICache& b = *base;
return b.getValue().at(path);
}
else
{
if (lastRefresh.time_since_epoch().count() == 0)
{
// No value has been requested yet
throw HueException(CURRENT_FILE_INFO,
"Tried to call const getValue(), but no value was cached. "
"Call refresh() or non-const getValue() first.");
}
return value;
}
}
std::chrono::steady_clock::duration APICache::getRefreshDuration() const
{
return refreshDuration;
}
HueCommandAPI& APICache::getCommandAPI()
{
return commands;
}
const HueCommandAPI& APICache::getCommandAPI() const
{
return commands;
}
bool APICache::needsRefresh()
{
using clock = std::chrono::steady_clock;
if (base)
{
// Update lastRefresh in case base was refreshed
lastRefresh = std::max(lastRefresh, base->lastRefresh);
}
// Explicitly check for zero in case refreshDuration is duration::max()
// Negative duration causes overflow check to overflow itself
if (lastRefresh.time_since_epoch().count() == 0 || refreshDuration.count() < 0)
{
// No value set yet
return true;
}
// Check if nextRefresh would overflow (assumes lastRefresh is not negative, which it should not be).
// If addition would overflow, do not refresh
else if (clock::duration::max() - refreshDuration > lastRefresh.time_since_epoch())
{
clock::time_point nextRefresh = lastRefresh + refreshDuration;
if (clock::now() >= nextRefresh)
{
return true;
}
}
return false;
}
std::string APICache::getRequestPath() const
{
std::string result;
if (base)
{
result = base->getRequestPath();
result.push_back('/');
}
result.append(path);
return result;
}
} // namespace hueplusplus