refactor: small again (#5666)

* refactor: restore the non-small parts of 5654

* refactor: restore the peer-mgr-active-requests parts of 5654

* chore: iwyu evbuffer in web.h

libtransmission/announcer-udp.cc

@@ -50,6 +50,7 @@ using tau_connection_t = uint64_t;
 using tau_transaction_t = uint32_t;
 
 using InBuf = libtransmission::BufferReader<std::byte>;
+using PayloadBuffer = libtransmission::Buffer;
 
 constexpr auto TauConnectionTtlSecs = time_t{ 45 };
 
@@ -85,7 +86,7 @@ struct tau_scrape_request
         }
 
         // build the payload
-        auto buf = libtransmission::Buffer{};
+        auto buf = PayloadBuffer{};
         buf.add_uint32(TAU_ACTION_SCRAPE);
         buf.add_uint32(transaction_id);
         for (int i = 0; i < in.info_hash_count; ++i)
@@ -179,7 +180,7 @@ struct tau_announce_request
         response.info_hash = in.info_hash;
 
         // build the payload
-        auto buf = libtransmission::Buffer{};
+        auto buf = PayloadBuffer{};
         buf.add_uint32(TAU_ACTION_ANNOUNCE);
         buf.add_uint32(transaction_id);
         buf.add(in.info_hash);
@@ -374,7 +375,7 @@ struct tau_tracker
             this->connection_transaction_id = tau_transaction_new();
             logtrace(this->key, fmt::format("Trying to connect. Transaction ID is {}", this->connection_transaction_id));
 
-            auto buf = libtransmission::Buffer{};
+            auto buf = PayloadBuffer{};
             buf.add_uint64(0x41727101980LL);
             buf.add_uint32(TAU_ACTION_CONNECT);
             buf.add_uint32(this->connection_transaction_id);
@@ -462,7 +463,7 @@ private:
     {
         if (this->connecting_at != 0 && this->connecting_at + ConnectionRequestTtl < now)
         {
-            auto empty_buf = libtransmission::Buffer{};
+            auto empty_buf = PayloadBuffer{};
             on_connection_response(TAU_ACTION_ERROR, empty_buf);
         }
 
@@ -535,7 +536,7 @@ private:
     {
         logdbg(this->key, fmt::format("sending request w/connection id {}", this->connection_id));
 
-        auto buf = libtransmission::Buffer{};
+        auto buf = PayloadBuffer{};
         buf.add_uint64(this->connection_id);
         buf.add(payload, payload_len);
 
@@ -622,7 +623,7 @@ public:
         }
 
         // extract the action_id and see if it makes sense
-        auto buf = libtransmission::Buffer{};
+        auto buf = PayloadBuffer{};
         buf.add(msg, msglen);
         auto const action_id = static_cast<tau_action_t>(buf.to_uint32());
 

libtransmission/peer-io.cc

@@ -419,7 +419,7 @@ size_t tr_peerIo::try_read(size_t max)
 
     auto& buf = inbuf_;
     tr_error* error = nullptr;
-    auto const n_read = socket_.try_read(buf, max, &error);
+    auto const n_read = socket_.try_read(buf, max, std::empty(buf), &error);
     set_enabled(Dir, error == nullptr || canRetryFromError(error->code));
 
     if (error != nullptr)

libtransmission/peer-io.h

@@ -15,6 +15,8 @@
 #include <memory>
 #include <utility> // std::pair
 
+#include <event2/util.h> // for evutil_socket_t
+
 #include "transmission.h"
 
 #include "bandwidth.h"
@@ -289,8 +291,11 @@ public:
     static void utp_init(struct_utp_context* ctx);
 
 private:
+    // our target socket receive buffer size
     static constexpr auto RcvBuf = size_t{ 256 * 1024 };
 
+    using PeerBuffer = libtransmission::Buffer;
+
     friend class libtransmission::test::HandshakeTest;
 
     [[nodiscard]] constexpr auto is_seed() const noexcept
@@ -342,8 +347,8 @@ private:
 
     tr_sha1_digest_t info_hash_;
 
-    libtransmission::Buffer inbuf_;
+    PeerBuffer inbuf_;
-    libtransmission::Buffer outbuf_;
+    PeerBuffer outbuf_;
 
     tr_session* const session_;
 

libtransmission/peer-mgr-active-requests.cc

@@ -11,53 +11,16 @@
 #include <unordered_set>
 #include <vector>
 
+#include <small/map.hpp>
+
 #define LIBTRANSMISSION_PEER_MODULE
 
 #include "libtransmission/transmission.h"
 
 #include "libtransmission/peer-mgr-active-requests.h"
+#include "libtransmission/peer-mgr-wishlist.h"
 #include "libtransmission/tr-assert.h"
 
-namespace
-{
-
-struct peer_at
-{
-    tr_peer* peer;
-    time_t when;
-
-    peer_at(tr_peer* p, time_t w)
-        : peer{ p }
-        , when{ w }
-    {
-    }
-
-    [[nodiscard]] int compare(peer_at const& that) const // <=>
-    {
-        if (peer != that.peer)
-        {
-            return peer < that.peer ? -1 : 1;
-        }
-
-        return 0;
-    }
-
-    bool operator==(peer_at const& that) const
-    {
-        return compare(that) == 0;
-    }
-};
-
-struct PeerAtHash
-{
-    std::size_t operator()(peer_at const& pa) const noexcept
-    {
-        return std::hash<tr_peer*>{}(pa.peer);
-    }
-};
-
-} // namespace
-
 class ActiveRequests::Impl
 {
 public:
@@ -97,7 +60,7 @@ public:
 
     std::unordered_map<tr_peer const*, size_t> count_;
 
-    std::unordered_map<tr_block_index_t, std::unordered_set<peer_at, PeerAtHash>> blocks_;
+    std::unordered_map<tr_block_index_t, small::map<tr_peer const*, time_t, Wishlist::EndgameMaxPeers>> blocks_;
 
 private:
     size_t size_ = 0;
@@ -126,8 +89,7 @@ bool ActiveRequests::add(tr_block_index_t block, tr_peer* peer, time_t when)
 bool ActiveRequests::remove(tr_block_index_t block, tr_peer const* peer)
 {
     auto const it = impl_->blocks_.find(block);
-    auto const key = peer_at{ const_cast<tr_peer*>(peer), 0 };
+    auto const removed = it != std::end(impl_->blocks_) && it->second.erase(peer) != 0;
-    auto const removed = it != std::end(impl_->blocks_) && it->second.erase(key) != 0;
 
     if (removed)
     {
@@ -148,10 +110,9 @@ std::vector<tr_block_index_t> ActiveRequests::remove(tr_peer const* peer)
     auto removed = std::vector<tr_block_index_t>{};
     removed.reserve(impl_->blocks_.size());
 
-    auto const key = peer_at{ const_cast<tr_peer*>(peer), 0 };
     for (auto const& [block, peers_at] : impl_->blocks_)
     {
-        if (peers_at.count(key) != 0U)
+        if (peers_at.count(peer) != 0U)
         {
             removed.push_back(block);
         }
@@ -178,7 +139,7 @@ std::vector<tr_peer*> ActiveRequests::remove(tr_block_index_t block)
             std::begin(it->second),
             std::end(it->second),
             std::begin(removed),
-            [](auto const& sent) { return sent.peer; });
+            [](auto const& iter) { return const_cast<tr_peer*>(iter.first); });
         impl_->blocks_.erase(block);
     }
 
@@ -193,8 +154,8 @@ std::vector<tr_peer*> ActiveRequests::remove(tr_block_index_t block)
 // return true if there's an active request to `peer` for `block`
 bool ActiveRequests::has(tr_block_index_t block, tr_peer const* peer) const
 {
-    auto const it = impl_->blocks_.find(block);
+    auto const iter = impl_->blocks_.find(block);
-    return it != std::end(impl_->blocks_) && (it->second.count(peer_at{ const_cast<tr_peer*>(peer), 0 }) != 0U);
+    return iter != std::end(impl_->blocks_) && (iter->second.count(peer) != 0U);
 }
 
 // count how many peers we're asking for `block`
@@ -225,11 +186,11 @@ std::vector<std::pair<tr_block_index_t, tr_peer*>> ActiveRequests::sentBefore(ti
 
     for (auto const& [block, peers_at] : impl_->blocks_)
     {
-        for (auto const& sent : peers_at)
+        for (auto const& [peer, sent_at] : peers_at)
         {
-            if (sent.when < when)
+            if (sent_at < when)
             {
-                sent_before.emplace_back(block, sent.peer);
+                sent_before.emplace_back(block, const_cast<tr_peer*>(peer));
             }
         }
     }

libtransmission/peer-mgr-wishlist.h

@@ -22,6 +22,8 @@
 class Wishlist
 {
 public:
+    static auto constexpr EndgameMaxPeers = size_t{ 2U };
+
     struct Mediator
     {
         [[nodiscard]] virtual bool clientCanRequestBlock(tr_block_index_t block) const = 0;

libtransmission/peer-socket.cc

@@ -70,7 +70,7 @@ void tr_peer_socket::close()
     handle = {};
 }
 
-size_t tr_peer_socket::try_write(Buffer& buf, size_t max, tr_error** error) const
+size_t tr_peer_socket::try_write(OutBuf& buf, size_t max, tr_error** error) const
 {
     if (max == size_t{})
     {
@@ -107,7 +107,7 @@ size_t tr_peer_socket::try_write(Buffer& buf, size_t max, tr_error** error) cons
     return {};
 }
 
-size_t tr_peer_socket::try_read(Buffer& buf, size_t max, tr_error** error) const
+size_t tr_peer_socket::try_read(InBuf& buf, size_t max, [[maybe_unused]] bool buf_is_empty, tr_error** error) const
 {
     if (max == size_t{})
     {
@@ -123,7 +123,7 @@ size_t tr_peer_socket::try_read(Buffer& buf, size_t max, tr_error** error) const
     // utp_read_drained() notifies libutp that this read buffer is empty.
     // It opens up the congestion window by sending an ACK (soonish) if
     // one was not going to be sent.
-    if (is_utp() && std::empty(buf))
+    if (is_utp() && buf_is_empty)
     {
         utp_read_drained(handle.utp);
     }

libtransmission/peer-socket.h

@@ -27,7 +27,8 @@ struct tr_session;
 class tr_peer_socket
 {
 public:
-    using Buffer = libtransmission::Buffer;
+    using InBuf = libtransmission::BufferWriter<std::byte>;
+    using OutBuf = libtransmission::BufferReader<std::byte>;
 
     tr_peer_socket() = default;
     tr_peer_socket(tr_session const* session, tr_address const& address, tr_port port, tr_socket_t sock);
@@ -56,8 +57,8 @@ public:
     }
     void close();
 
-    size_t try_write(Buffer& buf, size_t max, tr_error** error) const;
+    size_t try_read(InBuf& buf, size_t max, bool buf_is_empty, tr_error** error) const;
-    size_t try_read(Buffer& buf, size_t max, tr_error** error) const;
+    size_t try_write(OutBuf& buf, size_t max, tr_error** error) const;
 
     [[nodiscard]] constexpr std::pair<tr_address, tr_port> socketAddress() const noexcept
     {

libtransmission/web.h

@@ -14,6 +14,8 @@
 #include <string_view>
 #include <utility>
 
+#include <event2/buffer.h>
+
 struct evbuffer;
 
 class tr_web