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Maps: Limit parallel downloading of tiles

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Previously we would bombard RequestServer with as many requests as it
would take, but when frantically zooming in and out, we would run out of
fd's causing the Maps application to hang.

This implements a tile download queue and limits the amount of parallel
downloads to 8. This fixes the hangs accompanied by this debug console
message:

    Peer endpoint error: recvfd: Too many open files (errno=24)

It does not fix other sporadic hangs caused by requests that are never
finished, however.
This commit is contained in:
Jelle Raaijmakers 2023-09-05 16:19:06 +02:00
parent 494a8cb816
commit cf898f08ab
2 changed files with 57 additions and 16 deletions
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59
Userland/Applications/Maps/MapWidget.cpp
View file

@ -1,5 +1,6 @@
/*
* Copyright (c) 2023, Bastiaan van der Plaat <bastiaan.v.d.plaat@gmail.com>
* Copyright (c) 2023, Jelle Raaijmakers <jelle@gmta.nl>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -59,6 +60,13 @@ MapWidget::MapWidget(Options const& options)
m_request_client = Protocol::RequestClient::try_create().release_value_but_fixme_should_propagate_errors();
}
void MapWidget::set_zoom(int zoom)
{
m_zoom = min(max(zoom, ZOOM_MIN), ZOOM_MAX);
clear_tile_queue();
update();
}
void MapWidget::mousedown_event(GUI::MouseEvent& event)
{
if (m_connection_failed)
@ -145,30 +153,51 @@ void MapWidget::mousewheel_event(GUI::MouseEvent& event)
Optional<RefPtr<Gfx::Bitmap>> MapWidget::get_tile_image(int x, int y)
{
// Get the right tile from tiles cache
TileKey key = { x, y, m_zoom };
// Get the tile from tiles cache
TileKey const key = { x, y, m_zoom };
if (auto it = m_tiles.find(key); it != m_tiles.end()) {
if (it->value)
return it->value;
return {};
}
// Add tile when not in tiles
// Register an empty tile so we don't send requests multiple times
if (m_tiles.size() >= TILES_CACHE_MAX)
m_tiles.remove(m_tiles.begin());
m_tiles.set(key, nullptr);
// Schedule the tile download
m_tile_queue.enqueue(key);
process_tile_queue();
return {};
}
void MapWidget::process_tile_queue()
{
if (m_active_requests.size() >= TILES_DOWNLOAD_PARALLEL_MAX)
return;
if (m_tile_queue.is_empty())
return;
auto tile_key = m_tile_queue.dequeue();
// Start HTTP GET request to load image
HashMap<DeprecatedString, DeprecatedString> headers;
headers.set("User-Agent", "SerenityOS Maps");
headers.set("Accept", "image/png");
URL url(MUST(String::formatted(m_tile_layer_url, m_zoom, x, y)));
URL url(MUST(String::formatted(m_tile_layer_url, tile_key.zoom, tile_key.x, tile_key.y)));
auto request = m_request_client->start_request("GET", url, headers, {});
VERIFY(!request.is_null());
m_active_requests.append(request);
request->on_buffered_request_finish = [this, request, url, key](bool success, auto, auto&, auto, ReadonlyBytes payload) {
m_active_requests.remove_all_matching([request](auto const& other_request) { return other_request->id() == request->id(); });
request->on_buffered_request_finish = [this, request, url, tile_key](bool success, auto, auto&, auto, ReadonlyBytes payload) {
auto was_active = m_active_requests.remove_first_matching([request](auto const& other_request) { return other_request->id() == request->id(); });
if (!was_active)
return;
deferred_invoke([this]() { this->process_tile_queue(); });
// When first image load fails set connection failed
if (!success) {
// When first image load fails set connection failed
if (!m_first_image_loaded) {
m_first_image_loaded = true;
m_connection_failed = true;
@ -184,14 +213,24 @@ Optional<RefPtr<Gfx::Bitmap>> MapWidget::get_tile_image(int x, int y)
dbgln("Maps: Can't decode image: {}", url);
return;
}
m_tiles.set(key, decoder->frame(0).release_value_but_fixme_should_propagate_errors().image);
m_tiles.set(tile_key, decoder->frame(0).release_value_but_fixme_should_propagate_errors().image);
// FIXME: only update the part of the screen that this tile covers
update();
};
request->set_should_buffer_all_input(true);
request->on_certificate_requested = []() -> Protocol::Request::CertificateAndKey { return {}; };
}
// Return no image for now
return {};
void MapWidget::clear_tile_queue()
{
m_tile_queue.clear();
// FIXME: ideally we would like to abort all active requests here, but invoking `->stop()`
// often causes hangs for me for some reason.
m_active_requests.clear_with_capacity();
m_tiles.remove_all_matching([](auto, auto const& value) -> bool { return !value; });
}
void MapWidget::paint_tiles(GUI::Painter& painter)