Improve error reporting for estimaterawfee

src/rpc/mining.cpp

@@ -849,17 +849,17 @@ UniValue estimaterawfee(const JSONRPCRequest& request)
             "confirmation within nblocks blocks if possible. Uses virtual transaction size as defined\n"
             "in BIP 141 (witness data is discounted).\n"
             "\nArguments:\n"
-            "1. nblocks     (numeric)\n"
+            "1. nblocks     (numeric) Confirmation target in blocks (1 - 1008)\n"
             "2. threshold   (numeric, optional) The proportion of transactions in a given feerate range that must have been\n"
             "               confirmed within nblocks in order to consider those feerates as high enough and proceed to check\n"
             "               lower buckets.  Default: 0.95\n"
             "\nResult:\n"
             "{\n"
-            "  \"short\" : {            (json object) estimate for short time horizon\n"
+            "  \"short\" : {            (json object, optional) estimate for short time horizon\n"
-            "      \"feerate\" : x.x,        (numeric) estimate fee-per-kilobyte (in BTC)\n"
+            "      \"feerate\" : x.x,        (numeric, optional) estimate fee-per-kilobyte (in BTC)\n"
             "      \"decay\" : x.x,          (numeric) exponential decay (per block) for historical moving average of confirmation data\n"
             "      \"scale\" : x,            (numeric) The resolution of confirmation targets at this time horizon\n"
-            "      \"pass\" : {              (json object) information about the lowest range of feerates to succeed in meeting the threshold\n"
+            "      \"pass\" : {              (json object, optional) information about the lowest range of feerates to succeed in meeting the threshold\n"
             "          \"startrange\" : x.x,     (numeric) start of feerate range\n"
             "          \"endrange\" : x.x,       (numeric) end of feerate range\n"
             "          \"withintarget\" : x.x,   (numeric) number of txs over history horizon in the feerate range that were confirmed within target\n"
@@ -867,13 +867,14 @@ UniValue estimaterawfee(const JSONRPCRequest& request)
             "          \"inmempool\" : x.x,      (numeric) current number of txs in mempool in the feerate range unconfirmed for at least target blocks\n"
             "          \"leftmempool\" : x.x,    (numeric) number of txs over history horizon in the feerate range that left mempool unconfirmed after target\n"
             "      },\n"
-            "      \"fail\" : { ... },        (json object) information about the highest range of feerates to fail to meet the threshold\n"
+            "      \"fail\" : { ... },       (json object, optional) information about the highest range of feerates to fail to meet the threshold\n"
+            "      \"errors\":  [ str... ]   (json array of strings, optional) Errors encountered during processing\n"
             "  },\n"
-            "  \"medium\" : { ... },      (json object) estimate for medium time horizon\n"
+            "  \"medium\" : { ... },    (json object, optional) estimate for medium time horizon\n"
             "  \"long\" : { ... }       (json object) estimate for long time horizon\n"
             "}\n"
             "\n"
-            "A negative feerate is returned if no answer can be given.\n"
+            "Results are returned for any horizon which tracks blocks up to the confirmation target.\n"
             "\nExample:\n"
             + HelpExampleCli("estimaterawfee", "6 0.9")
             );
@@ -881,23 +882,29 @@ UniValue estimaterawfee(const JSONRPCRequest& request)
     RPCTypeCheck(request.params, {UniValue::VNUM, UniValue::VNUM, UniValue::VNUM}, true);
     RPCTypeCheckArgument(request.params[0], UniValue::VNUM);
     int nBlocks = request.params[0].get_int();
+    if (nBlocks < 1 || (unsigned int)nBlocks > ::feeEstimator.HighestTargetTracked(FeeEstimateHorizon::LONG_HALFLIFE)) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid nblocks");
+    }
     double threshold = 0.95;
     if (!request.params[1].isNull()) {
         threshold = request.params[1].get_real();
     }
+    if (threshold < 0 || threshold > 1) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid threshold");
+    }
 
     UniValue result(UniValue::VOBJ);
 
     for (FeeEstimateHorizon horizon : {FeeEstimateHorizon::SHORT_HALFLIFE, FeeEstimateHorizon::MED_HALFLIFE, FeeEstimateHorizon::LONG_HALFLIFE}) {
         CFeeRate feeRate;
         EstimationResult buckets;
-        feeRate = ::feeEstimator.estimateRawFee(nBlocks, threshold, horizon, &buckets);
 
+        // Only output results for horizons which track the target
+        if ((unsigned int)nBlocks > ::feeEstimator.HighestTargetTracked(horizon)) continue;
+
+        feeRate = ::feeEstimator.estimateRawFee(nBlocks, threshold, horizon, &buckets);
         UniValue horizon_result(UniValue::VOBJ);
-        horizon_result.push_back(Pair("feerate", feeRate == CFeeRate(0) ? -1.0 : ValueFromAmount(feeRate.GetFeePerK())));
+        UniValue errors(UniValue::VARR);
-        if (!(feeRate == CFeeRate(0))) {
-            horizon_result.push_back(Pair("decay", buckets.decay));
-            horizon_result.push_back(Pair("scale", (int)buckets.scale));
         UniValue passbucket(UniValue::VOBJ);
         passbucket.push_back(Pair("startrange", round(buckets.pass.start)));
         passbucket.push_back(Pair("endrange", round(buckets.pass.end)));
@@ -905,7 +912,6 @@ UniValue estimaterawfee(const JSONRPCRequest& request)
         passbucket.push_back(Pair("totalconfirmed", round(buckets.pass.totalConfirmed * 100.0) / 100.0));
         passbucket.push_back(Pair("inmempool", round(buckets.pass.inMempool * 100.0) / 100.0));
         passbucket.push_back(Pair("leftmempool", round(buckets.pass.leftMempool * 100.0) / 100.0));
-            horizon_result.push_back(Pair("pass", passbucket));
         UniValue failbucket(UniValue::VOBJ);
         failbucket.push_back(Pair("startrange", round(buckets.fail.start)));
         failbucket.push_back(Pair("endrange", round(buckets.fail.end)));
@@ -913,7 +919,22 @@ UniValue estimaterawfee(const JSONRPCRequest& request)
         failbucket.push_back(Pair("totalconfirmed", round(buckets.fail.totalConfirmed * 100.0) / 100.0));
         failbucket.push_back(Pair("inmempool", round(buckets.fail.inMempool * 100.0) / 100.0));
         failbucket.push_back(Pair("leftmempool", round(buckets.fail.leftMempool * 100.0) / 100.0));
+
+        // CFeeRate(0) is used to indicate error as a return value from estimateRawFee
+        if (feeRate != CFeeRate(0)) {
+            horizon_result.push_back(Pair("feerate", ValueFromAmount(feeRate.GetFeePerK())));
+            horizon_result.push_back(Pair("decay", buckets.decay));
+            horizon_result.push_back(Pair("scale", (int)buckets.scale));
+            horizon_result.push_back(Pair("pass", passbucket));
+            // buckets.fail.start == -1 indicates that all buckets passed, there is no fail bucket to output
+            if (buckets.fail.start != -1) horizon_result.push_back(Pair("fail", failbucket));
+        } else {
+            // Output only information that is still meaningful in the event of error
+            horizon_result.push_back(Pair("decay", buckets.decay));
+            horizon_result.push_back(Pair("scale", (int)buckets.scale));
             horizon_result.push_back(Pair("fail", failbucket));
+            errors.push_back("Insufficient data or no feerate found which meets threshold");
+            horizon_result.push_back(Pair("errors",errors));
         }
         result.push_back(Pair(StringForFeeEstimateHorizon(horizon), horizon_result));
     }