Add zero-confirmation support to webhooks (only) (#72)

src/db/data.cpp

@@ -34,6 +34,7 @@
 #include "wire/json/write.h"
 #include "wire/msgpack.h"
 #include "wire/uuid.h"
+#include "wire/wrapper/defaulted.h"
 
 namespace lws
 {
@@ -126,9 +127,11 @@ namespace db
     const auto payment_id = payment_bytes.empty() ?
       nullptr : std::addressof(payment_bytes);
 
+    // defaulted will omit "id" and "block" when the output is in the
+    // txpool with no valid values.
     wire::object(dest,
-      wire::field<0>("id", std::cref(self.spend_meta.id)),
-      wire::field<1>("block", self.link.height),
+      wire::optional_field<0>("id", wire::defaulted(std::cref(self.spend_meta.id), output_id::txpool())),
+      wire::optional_field<1>("block", wire::defaulted(self.link.height, block_id::txpool)),
       wire::field<2>("index", self.spend_meta.index),
       wire::field<3>("amount", self.spend_meta.amount),
       wire::field<4>("timestamp", self.timestamp),

src/db/data.h

@@ -30,6 +30,7 @@
 #include <cassert>
 #include <cstdint>
 #include <iosfwd>
+#include <limits>
 #include <string>
 #include <utility>
 
@@ -63,12 +64,19 @@ namespace db
   WIRE_AS_INTEGER(account_time);
 
   //! References a block height
-  enum class block_id : std::uint64_t {};
+  enum class block_id : std::uint64_t
+  {
+    txpool = std::uint64_t(-1) //! Represents not-yet-a-block
+  };
   WIRE_AS_INTEGER(block_id);
 
   //! References a global output number, as determined by the public chain
   struct output_id
   {
+    //! \return Special ID for outputs not yet in a block.
+    static constexpr output_id txpool() noexcept
+    { return {0, std::numeric_limits<std::uint64_t>::max()}; }
+
     std::uint64_t high; //!< Amount on public chain; rct outputs are `0`
     std::uint64_t low;  //!< Offset within `amount` on the public chain
   };

src/db/storage.cpp

@@ -749,6 +749,42 @@ namespace db
     return requests.get_value<request_info>(value);
   }
 
+  expect<std::vector<webhook_value>>
+  storage_reader::find_webhook(webhook_key const& key, crypto::hash8 const& payment_id, cursor::webhooks cur)
+  {
+    MONERO_PRECOND(txn != nullptr);
+    assert(db != nullptr);
+    MONERO_CHECK(check_cursor(*txn, db->tables.webhooks, cur));
+
+    webhook_dupsort dup{};
+
+    static_assert(sizeof(dup.payment_id) == sizeof(payment_id), "bad memcpy");
+    std::memcpy(std::addressof(dup.payment_id), std::addressof(payment_id), sizeof(payment_id));
+
+    MDB_val lkey = lmdb::to_val(key);
+    MDB_val lvalue = lmdb::to_val(dup);
+
+    std::vector<webhook_value> result{};
+    int err = mdb_cursor_get(cur.get(), &lkey, &lvalue, MDB_GET_BOTH_RANGE);
+    for (;;)
+    {
+      if (err)
+      {
+        if (err == MDB_NOTFOUND)
+          break;
+        return {lmdb::error(err)};
+      }
+
+      if (webhooks.get_fixed_value<MONERO_FIELD(webhook_dupsort, payment_id)>(lvalue) != dup.payment_id)
+        break;
+
+      result.push_back(MONERO_UNWRAP(webhooks.get_value(lvalue)));
+      err = mdb_cursor_get(cur.get(), &lkey, &lvalue, MDB_NEXT_DUP);
+    }
+
+    return result;
+  }
+
   expect<std::vector<std::pair<webhook_key, std::vector<webhook_value>>>>
   storage_reader::get_webhooks(cursor::webhooks cur)
   {

src/db/storage.h

@@ -133,6 +133,10 @@ namespace db
     expect<request_info>
       get_request(request type, account_address const& address, cursor::requests cur = nullptr) noexcept;
 
+    //! \return All webhook values associated with user `key` and `payment_id`.
+    expect<std::vector<webhook_value>>
+      find_webhook(webhook_key const& key, crypto::hash8 const& payment_id, cursor::webhooks cur = nullptr);
+
     //! \return All webhooks in the DB
     expect<std::vector<std::pair<webhook_key, std::vector<webhook_value>>>>
       get_webhooks(cursor::webhooks cur = nullptr);