rpc: Expose g_is_mempool_loaded via getmempoolinfo and

/rest/mempool/info.json

And use it to fix a race condition in mempool_persist.py:
https://travis-ci.org/Empact/bitcoin/jobs/487577243

Since e.g. getrawmempool returns errors based on this status, this
enables users to test it for readiness.
Github-Pull: #2254
Rebased-From: 0169a75

doc/REST-interface.md

@@ -79,6 +79,7 @@ $ curl localhost:18332/rest/getutxos/checkmempool/b2cdfd7b89def827ff8af7cd9bff76
 
 Returns various information about the TX mempool.
 Only supports JSON as output format.
+* loaded : (boolean) if the mempool is fully loaded
 * size : (numeric) the number of transactions in the TX mempool
 * bytes : (numeric) size of the TX mempool in bytes
 

src/rpc/blockchain.cpp

@@ -14,6 +14,7 @@
 #include "kernel.h"
 #include "masternodeman.h"
 #include "policy/feerate.h"
+#include "policy/policy.h"
 #include "rpc/server.h"
 #include "sync.h"
 #include "txdb.h"
@@ -1149,9 +1150,13 @@ UniValue getchaintips(const JSONRPCRequest& request)
 UniValue mempoolInfoToJSON()
 {
     UniValue ret(UniValue::VOBJ);
+    ret.pushKV("loaded", g_is_mempool_loaded);
     ret.pushKV("size", (int64_t) mempool.size());
     ret.pushKV("bytes", (int64_t) mempool.GetTotalTxSize());
     ret.pushKV("usage", (int64_t) mempool.DynamicMemoryUsage());
+    size_t maxmempool = gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
+    ret.pushKV("mempoolminfee", ValueFromAmount(std::max(mempool.GetMinFee(maxmempool), ::minRelayTxFee).GetFeePerK()));
+    ret.pushKV("minrelaytxfee", ValueFromAmount(::minRelayTxFee.GetFeePerK()));
 
     return ret;
 }
@@ -1165,9 +1170,13 @@ UniValue getmempoolinfo(const JSONRPCRequest& request)
 
             "\nResult:\n"
             "{\n"
+            "  \"loaded\": true|false         (boolean) True if the mempool is fully loaded\n"
             "  \"size\": xxxxx                (numeric) Current tx count\n"
             "  \"bytes\": xxxxx               (numeric) Sum of all tx sizes\n"
             "  \"usage\": xxxxx               (numeric) Total memory usage for the mempool\n"
+            "  \"maxmempool\": xxxxx,         (numeric) Maximum memory usage for the mempool\n"
+            "  \"mempoolminfee\": xxxxx       (numeric) Minimum fee rate in " + CURRENCY_UNIT + "/kB for tx to be accepted. Is the maximum of minrelaytxfee and minimum mempool fee\n"
+            "  \"minrelaytxfee\": xxxxx       (numeric) Current minimum relay fee for transactions\n"
             "}\n"
 
             "\nExamples:\n" +

test/functional/mempool_persist.py

@@ -31,8 +31,14 @@
 
 """
 
+from decimal import Decimal
+import os
+
 from test_framework.test_framework import PivxTestFramework
-from test_framework.util import *
+from test_framework.util import (
+    assert_equal,
+    wait_until,
+)
 
 class MempoolPersistTest(PivxTestFramework):
     def set_test_params(self):
@@ -64,10 +70,12 @@ def run_test(self):
         self.start_node(1, extra_args=["-persistmempool=0"])
         self.start_node(0)
         self.start_node(2)
-        # Give pivxd a second to reload the mempool
-        wait_until(lambda: len(self.nodes[0].getrawmempool()) == 5, timeout=1)
-        wait_until(lambda: len(self.nodes[2].getrawmempool()) == 5, timeout=1)
-        # The others loaded their mempool. If node_1 loaded anything, we'd probably notice by now:
+
+        wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"], timeout=1)
+        wait_until(lambda: self.nodes[2].getmempoolinfo()["loaded"], timeout=1)
+        assert_equal(len(self.nodes[0].getrawmempool()), 5)
+        assert_equal(len(self.nodes[2].getrawmempool()), 5)
+        # The others have loaded their mempool. If node_1 loaded anything, we'd probably notice by now:
         assert_equal(len(self.nodes[1].getrawmempool()), 0)
 
         # Verify accounting of mempool transactions after restart is correct
@@ -77,38 +85,39 @@ def run_test(self):
         self.log.debug("Stop-start node0 with -persistmempool=0. Verify that it doesn't load its mempool.dat file.")
         self.stop_nodes()
         self.start_node(0, extra_args=["-persistmempool=0"])
-        # Give bitcoind a second to reload the mempool
-        time.sleep(1)
+        wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"])
         assert_equal(len(self.nodes[0].getrawmempool()), 0)
 
         self.log.debug("Stop-start node0. Verify that it has the transactions in its mempool.")
         self.stop_nodes()
         self.start_node(0)
-        wait_until(lambda: len(self.nodes[0].getrawmempool()) == 5)
+        wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"])
+        assert_equal(len(self.nodes[0].getrawmempool()), 5)
 
         # Following code is ahead of our current repository state. Future back port.
+        '''
+        mempooldat0 = os.path.join(self.nodes[0].datadir, 'regtest', 'mempool.dat')
+        mempooldat1 = os.path.join(self.nodes[1].datadir, 'regtest', 'mempool.dat')
+        self.log.debug("Remove the mempool.dat file. Verify that savemempool to disk via RPC re-creates it")
+        os.remove(mempooldat0)
+        self.nodes[0].savemempool()
+        assert os.path.isfile(mempooldat0)
+
+        self.log.debug("Stop nodes, make node1 use mempool.dat from node0. Verify it has 5 transactions")
+        os.rename(mempooldat0, mempooldat1)
+        self.stop_nodes()
+        self.start_node(1, extra_args=[])
+        wait_until(lambda: self.nodes[1].getmempoolinfo()["loaded"])
+        assert_equal(len(self.nodes[1].getrawmempool()), 5)
 
-        # mempooldat0 = os.path.join(self.options.tmpdir, 'node0', 'regtest', 'mempool.dat')
-        # mempooldat1 = os.path.join(self.options.tmpdir, 'node1', 'regtest', 'mempool.dat')
-        # self.log.debug("Remove the mempool.dat file. Verify that savemempool to disk via RPC re-creates it")
-        # os.remove(mempooldat0)
-        # self.nodes[0].savemempool()
-        # assert os.path.isfile(mempooldat0)
-        #
-        # self.log.debug("Stop nodes, make node1 use mempool.dat from node0. Verify it has 5 transactions")
-        # os.rename(mempooldat0, mempooldat1)
-        # self.stop_nodes()
-        # self.start_node(1, extra_args=[])
-        # wait_until(lambda: len(self.nodes[1].getrawmempool()) == 5)
-        #
-        # self.log.debug("Prevent bitcoind from writing mempool.dat to disk. Verify that `savemempool` fails")
-        # # to test the exception we are setting bad permissions on a tmp file called mempool.dat.new
-        # # which is an implementation detail that could change and break this test
-        # mempooldotnew1 = mempooldat1 + '.new'
-        # with os.fdopen(os.open(mempooldotnew1, os.O_CREAT, 0o000), 'w'):
-        #     pass
-        # assert_raises_rpc_error(-1, "Unable to dump mempool to disk", self.nodes[1].savemempool)
-        # os.remove(mempooldotnew1)
+        self.log.debug("Prevent bitcoind from writing mempool.dat to disk. Verify that `savemempool` fails")
+        # to test the exception we are creating a tmp folder called mempool.dat.new
+        # which is an implementation detail that could change and break this test
+        mempooldotnew1 = mempooldat1 + '.new'
+        os.mkdir(mempooldotnew1)
+        assert_raises_rpc_error(-1, "Unable to dump mempool to disk", self.nodes[1].savemempool)
+        os.rmdir(mempooldotnew1)
+        '''
 
 if __name__ == '__main__':
     MempoolPersistTest().main()