Add documentation describing CWallet::nTimeSmart.

Most of the text comes from the 2012 Luke Dashjr <luke-jr+git@utopios.org>
c3f95ef commit message.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index aefd152840..dc085d0dfd 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3454,6 +3454,27 @@ void CWallet::GetKeyBirthTimes(std::map<CTxDestination, int64_t> &mapKeyBirth) c
         mapKeyBirth[it->first] = it->second->GetBlockTime() - 7200; // block times can be 2h off
 }
 
+/**
+ * Compute smart timestamp for a transaction being added to the wallet.
+ *
+ * Logic:
+ * - If sending a transaction, assign its timestamp to the current time.
+ * - If receiving a transaction outside a block, assign its timestamp to the
+ *   current time.
+ * - If receiving a block with a future timestamp, assign all its (not already
+ *   known) transactions' timestamps to the current time.
+ * - If receiving a block with a past timestamp, before the most recent known
+ *   transaction (that we care about), assign all its (not already known)
+ *   transactions' timestamps to the same timestamp as that most-recent-known
+ *   transaction.
+ * - If receiving a block with a past timestamp, but after the most recent known
+ *   transaction, assign all its (not already known) transactions' timestamps to
+ *   the block time.
+ *
+ * For more information see CWalletTx::nTimeSmart,
+ * https://bitcointalk.org/?topic=54527, or
+ * https://github.com/bitcoin/bitcoin/pull/1393.
+ */
 unsigned int CWallet::ComputeTimeSmart(const CWalletTx& wtx) const
 {
     unsigned int nTimeSmart = wtx.nTimeReceived;