Merge #12507: Interrupt rescan on shutdown request

c4fda76 wallet: Interrupt rescan on shutdown request (João Barbosa)

Pull request description:

  Fixes #10987.

  Here are the steps to test the feature:

  1. start bitcoind, generate a couple of transactions and then stop:
  ```
  bitcoind -regtest -printtoconsole
  bitcoin-cli -regtest generate 100
  ```
  2. apply the following patch
  ```diff
  diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
  index 2478d67ce..8f8cea40c 100644
  --- a/src/wallet/wallet.cpp
  +++ b/src/wallet/wallet.cpp
  @@ -1671,6 +1671,7 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, CBlock
           }
           while (pindex && !fAbortRescan && !ShutdownRequested())
           {
  +            MilliSleep(500);
               if (pindex->nHeight % 100 == 0 && dProgressTip - dProgressStart > 0.0) {
                   double gvp = 0;
                   {
  ```
  3. start bitcoind with rescan flag, interrupt with CTRL+C and the output should look like:
  ```
  bitcoind -regtest -printtoconsole -rescan
  ...
  ^C2018-02-22 01:00:55 AddToWallet e8bfb4501b630ad2acb91e88ab0112a779766536d2c564b04faae45ae90e18f7
  2018-02-22 01:00:55 Rescan interrupted by shutdown request at block 5. Progress=1.000000
  2018-02-22 01:00:55  rescan                 1774ms
  2018-02-22 01:00:55 setKeyPool.size() = 1995
  2018-02-22 01:00:55 mapWallet.size() = 10145
  2018-02-22 01:00:55 mapAddressBook.size() = 3
  2018-02-22 01:00:55 Shutdown: In progress...
  2018-02-22 01:00:55 scheduler thread interrupt
  2018-02-22 01:00:55 Shutdown: done
  ```

Tree-SHA512: f9bebe2cdacf0359b6cbfcbc48ac2818a3ae7aa7822ff0c2c0de4ca2fff7c88493380b74a1c5ff2ce1de01fe605b0e5ef3576f124ea9cff8ef25a9e762477b92

Author: laanwj

src/wallet/wallet.cpp

@@ -11,6 +11,7 @@
 #include <consensus/consensus.h>
 #include <consensus/validation.h>
 #include <fs.h>
+#include <init.h>
 #include <key.h>
 #include <key_io.h>
 #include <keystore.h>
@@ -1753,7 +1754,7 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, CBlock
             dProgressTip = GuessVerificationProgress(chainParams.TxData(), tip);
         }
         double gvp = dProgressStart;
-        while (pindex && !fAbortRescan)
+        while (pindex && !fAbortRescan && !ShutdownRequested())
         {
             if (pindex->nHeight % 100 == 0 && dProgressTip - dProgressStart > 0.0) {
                 ShowProgress(_("Rescanning..."), std::max(1, std::min(99, (int)((gvp - dProgressStart) / (dProgressTip - dProgressStart) * 100))));
@@ -1794,6 +1795,8 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, CBlock
         }
         if (pindex && fAbortRescan) {
             LogPrintf("Rescan aborted at block %d. Progress=%f\n", pindex->nHeight, gvp);
+        } else if (pindex && ShutdownRequested()) {
+            LogPrintf("Rescan interrupted by shutdown request at block %d. Progress=%f\n", pindex->nHeight, gvp);
         }
         ShowProgress(_("Rescanning..."), 100); // hide progress dialog in GUI
     }