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feat: add libtransmission::Dns.cached() (#3984)

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This commit is contained in:
Charles Kerr
2022-10-17 20:17:01 -05:00
committed by GitHub
parent c8e652c820
commit 7ee76a604d
4 changed files with 84 additions and 35 deletions
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libtransmission/dns-ev.h
+42 -15
View File
@@ -86,22 +86,24 @@ public:
}
}
std::optional<std::pair<sockaddr const*, socklen_t>> cached(std::string_view address, Hints hints = {}) const override
{
if (auto const* entry = cached(makeKey(address, hints)); entry != nullptr)
{
return std::make_pair(reinterpret_cast<sockaddr const*>(&entry->ss_), entry->sslen_);
}
return {};
}
Tag lookup(std::string_view address, Callback&& callback, Hints hints = {}) override
{
auto const key = std::make_pair(tr_strlower(address), hints);
auto const now = time_func_();
auto const key = makeKey(address, hints);
if (auto iter = cache_.find(key); iter != std::end(cache_))
if (auto const* entry = cached(key); entry)
{
auto const& entry = iter->second;
if (entry.expires_at_ > now)
{
callback(reinterpret_cast<struct sockaddr const*>(&entry.ss_), entry.sslen_);
return {};
}
cache_.erase(iter); // expired
callback(reinterpret_cast<sockaddr const*>(&entry->ss_), entry->sslen_, entry->expires_at_);
return {};
}
auto& request = requests_[key];
@@ -131,7 +133,7 @@ public:
continue;
}
iter->callback_(nullptr, 0);
iter->callback_(nullptr, 0, 0);
request.callbacks.erase(iter);
@@ -148,6 +150,28 @@ public:
}
private:
[[nodiscard]] static Key makeKey(std::string_view address, Hints hints)
{
return Key{ tr_strlower(address), hints };
}
[[nodiscard]] CacheEntry const* cached(Key const& key) const
{
if (auto iter = cache_.find(key); iter != std::end(cache_))
{
auto const& entry = iter->second;
if (auto const now = time_func_(); entry.expires_at_ > now)
{
return &entry;
}
cache_.erase(iter); // expired
}
return nullptr;
}
static void evcallback(int /*result*/, struct evutil_addrinfo* res, void* varg)
{
auto* const arg = static_cast<CallbackArg*>(varg);
@@ -168,7 +192,10 @@ private:
{
for (auto& callback : request_entry.mapped().callbacks)
{
callback.callback_(reinterpret_cast<sockaddr const*>(&cache_entry.ss_), cache_entry.sslen_);
callback.callback_(
reinterpret_cast<sockaddr const*>(&cache_entry.ss_),
cache_entry.sslen_,
cache_entry.expires_at_);
}
}
}
@@ -176,7 +203,7 @@ private:
TimeFunc const time_func_;
static time_t constexpr CacheTtlSecs = 3600U;
std::unique_ptr<evdns_base, void (*)(evdns_base*)> const evdns_base_;
std::map<Key, CacheEntry> cache_;
mutable std::map<Key, CacheEntry> cache_;
std::map<Key, Request> requests_;
unsigned int next_tag_ = 1;
};
libtransmission/dns.h
+5 -1
View File
@@ -20,7 +20,7 @@ class Dns
public:
virtual ~Dns() = default;
using Callback = std::function<void(struct sockaddr const*, socklen_t salen)>;
using Callback = std::function<void(struct sockaddr const*, socklen_t salen, time_t expires_at)>;
using Tag = unsigned int;
class Hints
@@ -60,6 +60,10 @@ public:
}
};
[[nodiscard]] virtual std::optional<std::pair<struct sockaddr const*, socklen_t>> cached(
std::string_view address,
Hints hints = {}) const = 0;
virtual Tag lookup(std::string_view address, Callback&& callback, Hints hints = {}) = 0;
virtual void cancel(Tag) = 0;
tests/libtransmission/dns-test.cc
+30 -12
View File
@@ -41,7 +41,10 @@ protected:
::testing::Test::TearDown();
}
bool waitFor(struct event_base* evb, std::function<bool()> const& test, std::chrono::milliseconds msec = DefaultTimeout)
static bool waitFor(
struct event_base* evb,
std::function<bool()> const& test,
std::chrono::milliseconds msec = DefaultTimeout)
{
auto const deadline = std::chrono::steady_clock::now() + msec;
@@ -72,10 +75,11 @@ TEST_F(EvDnsTest, canLookup)
dns.lookup(
"example.com",
[&done](struct sockaddr const* ai, socklen_t ailen)
[&done](struct sockaddr const* ai, socklen_t ailen, time_t expires_at)
{
EXPECT_NE(nullptr, ai);
EXPECT_GT(ailen, 0);
EXPECT_GT(expires_at, tr_time());
done = true;
});
@@ -90,19 +94,21 @@ TEST_F(EvDnsTest, canRequestWhilePending)
dns.lookup(
"example.com",
[&n_done](struct sockaddr const* ai, socklen_t ailen)
[&n_done](struct sockaddr const* ai, socklen_t ailen, time_t expires_at)
{
EXPECT_NE(nullptr, ai);
EXPECT_GT(ailen, 0);
EXPECT_GT(expires_at, tr_time());
++n_done;
});
dns.lookup(
"example.com",
[&n_done](struct sockaddr const* ai, socklen_t ailen)
[&n_done](struct sockaddr const* ai, socklen_t ailen, time_t expires_at)
{
EXPECT_NE(nullptr, ai);
EXPECT_GT(ailen, 0);
EXPECT_GT(expires_at, tr_time());
++n_done;
});
@@ -115,26 +121,29 @@ TEST_F(EvDnsTest, canCancel)
{
auto dns = EvDns{ event_base_, tr_time };
auto n_done = size_t{ 0 };
static auto constexpr Name = "example.com"sv;
auto tag = dns.lookup(
"example.com",
[&n_done](struct sockaddr const* ai, socklen_t ailen)
Name,
[&n_done](struct sockaddr const* ai, socklen_t ailen, time_t expires_at)
{
++n_done;
// we cancelled this req, so `ai` and `ailen` should be zeroed out
EXPECT_EQ(nullptr, ai);
EXPECT_EQ(0, ailen);
EXPECT_EQ(0, expires_at);
});
dns.lookup(
"example.com",
[&n_done](struct sockaddr const* ai, socklen_t ailen)
Name,
[&n_done](struct sockaddr const* ai, socklen_t ailen, time_t expires_at)
{
++n_done;
// this one did _not_ get cancelled so it should be OK
EXPECT_NE(nullptr, ai);
EXPECT_GT(ailen, 0);
EXPECT_GT(expires_at, tr_time());
});
dns.cancel(tag);
@@ -147,15 +156,17 @@ TEST_F(EvDnsTest, canCancel)
TEST_F(EvDnsTest, doesCacheEntries)
{
auto dns = EvDns{ event_base_, tr_time };
static auto constexpr Name = "example.com"sv;
struct sockaddr const* ai_addr = nullptr;
dns.lookup(
"example.com",
[&ai_addr](struct sockaddr const* ai, socklen_t ailen)
Name,
[&ai_addr](struct sockaddr const* ai, socklen_t ailen, time_t expires_at)
{
EXPECT_NE(nullptr, ai);
EXPECT_GT(ailen, 0);
EXPECT_GT(expires_at, tr_time());
ai_addr = ai;
});
@@ -165,17 +176,24 @@ TEST_F(EvDnsTest, doesCacheEntries)
auto second_callback_called = false;
dns.lookup(
"example.com",
[&ai_addr, &second_callback_called](struct sockaddr const* ai, socklen_t ailen)
Name,
[&ai_addr, &second_callback_called](struct sockaddr const* ai, socklen_t ailen, time_t expires_at)
{
EXPECT_NE(nullptr, ai);
EXPECT_GT(ailen, 0);
EXPECT_EQ(ai_addr, ai);
EXPECT_GT(expires_at, tr_time());
second_callback_called = true;
});
// since it's cached, the callback should have been invoked
// without waiting for the event loop
EXPECT_TRUE(second_callback_called);
// confirm that `cached()` returns the cached value immediately
auto res = dns.cached(Name);
EXPECT_TRUE(res);
EXPECT_EQ(ai_addr, res->first);
EXPECT_GT(res->second, 0);
}
} // namespace libtransmission::test
tests/libtransmission/net-test.cc
+7 -7
View File
@@ -14,19 +14,19 @@ using namespace std::literals;
TEST_F(NetTest, conversionsIPv4)
{
auto constexpr port = tr_port::fromHost(80);
auto constexpr addrstr = "127.0.0.1"sv;
auto constexpr Port = tr_port::fromHost(80);
auto constexpr AddrStr = "127.0.0.1"sv;
auto addr = tr_address::fromString(addrstr);
auto addr = tr_address::fromString(AddrStr);
EXPECT_TRUE(addr);
EXPECT_EQ(addrstr, addr->readable());
EXPECT_EQ(AddrStr, addr->readable());
auto [ss, sslen] = addr->toSockaddr(port);
auto [ss, sslen] = addr->toSockaddr(Port);
EXPECT_EQ(AF_INET, ss.ss_family);
EXPECT_EQ(port.network(), reinterpret_cast<sockaddr_in const*>(&ss)->sin_port);
EXPECT_EQ(Port.network(), reinterpret_cast<sockaddr_in const*>(&ss)->sin_port);
auto addrport = tr_address::fromSockaddr(reinterpret_cast<sockaddr const*>(&ss));
EXPECT_TRUE(addrport);
EXPECT_EQ(addr, addrport->first);
EXPECT_EQ(port, addrport->second);
EXPECT_EQ(Port, addrport->second);
}