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#pragma once
#include <mbgl/tile/tile_loader.hpp>
#include <mbgl/storage/file_source.hpp>
#include <mbgl/renderer/tile_parameters.hpp>
#include <mbgl/util/tileset.hpp>
#include <cassert>
namespace mbgl {
template <typename T>
TileLoader<T>::TileLoader(T& tile_,
const OverscaledTileID& id,
const TileParameters& parameters,
const Tileset& tileset)
: tile(tile_),
necessity(Necessity::Optional),
resource(Resource::tile(
tileset.tiles.at(0),
parameters.pixelRatio,
id.canonical.x,
id.canonical.y,
id.canonical.z,
tileset.scheme)),
fileSource(parameters.fileSource) {
assert(!request);
if (fileSource.supportsOptionalRequests()) {
// When supported, the first request is always optional, even if the TileLoader
// is marked as required. That way, we can let the first optional request continue
// to load when the TileLoader is later changed from required to optional. If we
// started out with a required request, we'd have to cancel everything, including the
// initial optional part of the request.
loadOptional();
} else {
// When the FileSource doesn't support optional requests, we do nothing until the
// data is definitely required.
if (necessity == Necessity::Required) {
loadRequired();
} else {
// We're using this field to check whether the pending request is optional or required.
resource.necessity = Resource::Optional;
}
}
}
template <typename T>
TileLoader<T>::~TileLoader() = default;
template <typename T>
void TileLoader<T>::loadOptional() {
assert(!request);
resource.necessity = Resource::Optional;
request = fileSource.request(resource, [this](Response res) {
request.reset();
tile.setTriedOptional();
if (res.error && res.error->reason == Response::Error::Reason::NotFound) {
// When the optional request could not be satisfied, don't treat it as an error.
// Instead, we make sure that the next request knows that there has been an optional
// request before by setting one of the prior* fields.
resource.priorModified = res.modified;
resource.priorExpires = Timestamp{ Seconds::zero() };
resource.priorEtag = res.etag;
resource.priorData = res.data;
} else {
loadedData(res);
}
if (necessity == Necessity::Required) {
loadRequired();
}
});
}
template <typename T>
void TileLoader<T>::makeRequired() {
if (!request) {
loadRequired();
}
}
template <typename T>
void TileLoader<T>::makeOptional() {
if (resource.necessity == Resource::Required && request) {
// Abort a potential HTTP request.
request.reset();
}
}
template <typename T>
void TileLoader<T>::loadedData(const Response& res) {
if (res.error && res.error->reason != Response::Error::Reason::NotFound) {
tile.setError(std::make_exception_ptr(std::runtime_error(res.error->message)));
} else if (res.notModified) {
resource.priorExpires = res.expires;
// Do not notify the tile; when we get this message, it already has the current
// version of the data.
} else {
resource.priorModified = res.modified;
resource.priorExpires = res.expires;
resource.priorEtag = res.etag;
tile.setData(res.noContent ? nullptr : res.data, res.modified, res.expires);
}
}
template <typename T>
void TileLoader<T>::loadRequired() {
assert(!request);
resource.necessity = Resource::Required;
request = fileSource.request(resource, [this](Response res) { loadedData(res); });
}
} // namespace mbgl
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