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/*
* nghttp2 - HTTP/2 C Library
*
* Copyright (c) 2012 Tatsuhiro Tsujikawa
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef SHRPX_DOWNSTREAM_QUEUE_H
#define SHRPX_DOWNSTREAM_QUEUE_H
#include "shrpx.h"
#include <cinttypes>
#include <map>
#include <set>
#include <memory>
#include "template.h"
using namespace nghttp2;
namespace shrpx {
class Downstream;
// Link entry in HostEntry.blocked and downstream because downstream
// could be deleted in anytime and we'd like to find Downstream in
// O(1). Downstream has field to link back to this object.
struct BlockedLink {
Downstream *downstream;
BlockedLink *dlnext, *dlprev;
};
class DownstreamQueue {
public:
struct HostEntry {
HostEntry(ImmutableString &&key);
HostEntry(HostEntry &&) = default;
HostEntry &operator=(HostEntry &&) = default;
HostEntry(const HostEntry &) = delete;
HostEntry &operator=(const HostEntry &) = delete;
// Key that associates this object
ImmutableString key;
// Set of stream ID that blocked by conn_max_per_host_.
DList<BlockedLink> blocked;
// The number of connections currently made to this host.
size_t num_active;
};
using HostEntryMap = std::map<StringRef, HostEntry>;
// conn_max_per_host == 0 means no limit for downstream connection.
DownstreamQueue(size_t conn_max_per_host = 0, bool unified_host = true);
~DownstreamQueue();
// Add |downstream| to this queue. This is entry point for
// Downstream object.
void add_pending(std::unique_ptr<Downstream> downstream);
// Set |downstream| to failure state, which means that downstream
// failed to connect to backend.
void mark_failure(Downstream *downstream);
// Set |downstream| to active state, which means that downstream
// connection has started.
void mark_active(Downstream *downstream);
// Set |downstream| to blocked state, which means that download
// connection was blocked because conn_max_per_host_ limit.
void mark_blocked(Downstream *downstream);
// Returns true if we can make downstream connection to given
// |host|.
bool can_activate(const StringRef &host) const;
// Removes and frees |downstream| object. If |downstream| is in
// DispatchState::ACTIVE, and |next_blocked| is true, this function
// may return Downstream object with the same target host in
// DispatchState::BLOCKED if its connection is now not blocked by
// conn_max_per_host_ limit.
Downstream *remove_and_get_blocked(Downstream *downstream,
bool next_blocked = true);
Downstream *get_downstreams() const;
HostEntry &find_host_entry(const StringRef &host);
StringRef make_host_key(const StringRef &host) const;
StringRef make_host_key(Downstream *downstream) const;
private:
// Per target host structure to keep track of the number of
// connections to the same host.
HostEntryMap host_entries_;
DList<Downstream> downstreams_;
// Maximum number of concurrent connections to the same host.
size_t conn_max_per_host_;
// true if downstream host is treated as the same. Used for reverse
// proxying.
bool unified_host_;
};
} // namespace shrpx
#endif // SHRPX_DOWNSTREAM_QUEUE_H
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