From 0a215695a80f1cbceddd95ecfdf7dfb2c1f72ab6 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Wed, 28 Jun 2017 11:15:45 -0700
Subject: [PATCH] Merge #10685: Clarify CCoinsViewMemPool documentation.

381b8fc36 Clarify CCoinsViewMemPool documentation. (Matt Corallo)

Tree-SHA512: 0d1520595a03ea4038b4119871d79dfc28a50f42ac7667b30a583805d4fe4b0480a6912b9b4f7660c7223778ef85f2f9d1870551383a35c5e8c88cd2935f59d3
---
 src/rpc/blockchain.cpp | 2 +-
 src/txmempool.h        | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 73ce295ea4..71f5d00af0 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1229,7 +1229,7 @@ UniValue gettxout(const JSONRPCRequest& request)
     if (fMempool) {
         LOCK(mempool.cs);
         CCoinsViewMemPool view(pcoinsTip, mempool);
-        if (!view.GetCoin(out, coin) || mempool.isSpent(out)) { // TODO: filtering spent coins should be done by the CCoinsViewMemPool
+        if (!view.GetCoin(out, coin) || mempool.isSpent(out)) {
             return NullUniValue;
         }
     } else {
diff --git a/src/txmempool.h b/src/txmempool.h
index 775c987a83..6b1e1f117d 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -710,6 +710,13 @@ private:
 /** 
  * CCoinsView that brings transactions from a memorypool into view.
  * It does not check for spendings by memory pool transactions.
+ * Instead, it provides access to all Coins which are either unspent in the
+ * base CCoinsView, or are outputs from any mempool transaction!
+ * This allows transaction replacement to work as expected, as you want to
+ * have all inputs "available" to check signatures, and any cycles in the
+ * dependency graph are checked directly in AcceptToMemoryPool.
+ * It also allows you to sign a double-spend directly in signrawtransaction,
+ * as long as the conflicting transaction is not yet confirmed.
  */
 class CCoinsViewMemPool : public CCoinsViewBacked
 {