WIP: implemented keva_delete.

Problem: after the call, the corresponding keva coin is gone!

src/keva/common.cpp

@@ -22,7 +22,9 @@ CKevaData::fromScript (unsigned h, const COutPoint& out,
                        const CKevaScript& script)
 {
   if (script.isAnyUpdate()) {
+    if (!script.isDelete()) {
       value = script.getOpValue();
+    }
   } else if (script.isNamespaceRegistration()) {
     value = script.getOpNamespaceDisplayName();
   } else {

src/keva/main.cpp

@@ -58,6 +58,12 @@ CKevaMemPool::addUnchecked (const uint256& hash, const CTxMemPoolEntry& entry)
     const valtype& nameSpace = entry.getNamespace();
     listUnconfirmedKeyValues.push_back(std::make_tuple(hash, nameSpace, entry.getKey(), entry.getValue()));
   }
+
+  if (entry.isKeyDelete()) {
+    const valtype& nameSpace = entry.getNamespace();
+    const valtype& empty = ValtypeFromString("");
+    listUnconfirmedKeyValues.push_back(std::make_tuple(hash, nameSpace, entry.getKey(), empty));
+  }
 }
 
 bool
@@ -113,7 +119,7 @@ void CKevaMemPool::remove(const CTxMemPoolEntry& entry)
     }
   }
 
-  if (entry.isKeyUpdate()) {
+  if (entry.isKeyUpdate() || entry.isKeyDelete()) {
     auto hash = entry.GetTx().GetHash();
     for (auto iter = listUnconfirmedKeyValues.begin(); iter != listUnconfirmedKeyValues.end(); ++iter) {
       if (std::get<0>(*iter) == hash) {
@@ -190,6 +196,11 @@ CKevaMemPool::checkTx(const CTransaction& tx) const
         break;
       }
 
+      case OP_KEVA_DELETE:
+      {
+        break;
+      }
+
       default:
         assert (false);
     }
@@ -329,19 +340,29 @@ CheckKevaTransaction (const CTransaction& tx, unsigned nHeight,
     return state.Invalid (error ("CheckKevaTransaction: key too long"));
   }
 
+  const valtype& nameSpace = nameOpOut.getOpNamespace();
+  if (nameSpace != nameOpIn.getOpNamespace()) {
+    return state.Invalid(error("%s: KEVA_PUT namespace mismatch to prev tx found in %s", __func__, txid));
+  }
+
+  if (nameOpOut.getKevaOp() == OP_KEVA_PUT) {
     if (nameOpOut.getOpValue().size () > MAX_VALUE_LENGTH) {
       return state.Invalid (error ("CheckKevaTransaction: value too long"));
     }
 
-  /* Process KEVA_PUT next.  */
-  const valtype& nameSpace = nameOpOut.getOpNamespace();
-  if (nameOpOut.getKevaOp() == OP_KEVA_PUT) {
     if (!nameOpIn.isAnyUpdate() && !nameOpIn.isNamespaceRegistration()) {
       return state.Invalid(error("CheckKevaTransaction: KEVA_PUT with prev input that is no update"));
     }
+  }
 
-    if (nameSpace != nameOpIn.getOpNamespace()) {
+  if (nameOpOut.getKevaOp() == OP_KEVA_DELETE) {
-      return state.Invalid(error("%s: KEVA_PUT namespace mismatch to prev tx found in %s", __func__, txid));
+    if (!nameOpIn.isAnyUpdate() && !nameOpIn.isNamespaceRegistration()) {
+      return state.Invalid(error("CheckKevaTransaction: KEVA_DELETE with prev input that is no update"));
+    }
+    CKevaData data;
+    const bool hasKey = view.GetName(nameSpace, nameOpOut.getOpKey(), data);
+    if (!hasKey) {
+      return state.Invalid(error("CheckKevaTransaction: no key to delete"));
     }
   }
   return true;
@@ -362,7 +383,6 @@ void ApplyKevaTransaction(const CTransaction& tx, unsigned nHeight,
     if (!op.isKevaOp()) {
       continue;
     }
-
     if (op.isNamespaceRegistration()) {
       const valtype& nameSpace = op.getOpNamespace();
       const valtype& displayName = op.getOpNamespaceDisplayName();
@@ -389,11 +409,15 @@ void ApplyKevaTransaction(const CTransaction& tx, unsigned nHeight,
       undo.vkevaundo.push_back(opUndo);
 
       CKevaData data;
+      if (op.isDelete()) {
+        view.DeleteName(nameSpace, key);
+      } else {
         data.fromScript(nHeight, COutPoint(tx.GetHash(), i), op);
         view.SetName(nameSpace, key, data, false);
       }
     }
   }
+}
 
 void
 CheckNameDB (bool disconnect)

src/script/interpreter.cpp

@@ -359,6 +359,7 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 //
                 case OP_KEVA_NAMESPACE:
                 case OP_KEVA_PUT:
+                case OP_KEVA_DELETE:
                     break;
 
                 case OP_CHECKLOCKTIMEVERIFY:

src/script/keva.cpp

@@ -55,6 +55,12 @@ CKevaScript::CKevaScript (const CScript& script)
       }
       break;
 
+    case OP_KEVA_DELETE:
+      if (args.size() != 2) {
+        return;
+      }
+      break;
+
     case OP_KEVA_NAMESPACE:
       if (args.size() != 2) {
         return;
@@ -79,6 +85,15 @@ CKevaScript::buildKevaPut(const CScript& addr, const valtype& nameSpace,
   return prefix + addr;
 }
 
+CScript
+CKevaScript::buildKevaDelete(const CScript& addr, const valtype& nameSpace, const valtype& key)
+{
+  CScript prefix;
+  prefix << OP_KEVA_DELETE << nameSpace << key << OP_2DROP;
+
+  return prefix + addr;
+}
+
 CScript CKevaScript::buildKevaNamespace(const CScript& addr, const valtype& nameSpace,
                                 const valtype& displayName)
 {

src/script/keva.h

@@ -66,6 +66,9 @@ public:
       case OP_KEVA_NAMESPACE:
         return true;
 
+      case OP_KEVA_DELETE:
+        return true;
+
       case OP_NOP:
         return false;
 
@@ -94,6 +97,9 @@ public:
       case OP_KEVA_PUT:
         return op;
 
+      case OP_KEVA_DELETE:
+        return op;
+
       case OP_KEVA_NAMESPACE:
         return op;
 
@@ -115,6 +121,9 @@ public:
       case OP_KEVA_PUT:
         return false;
 
+      case OP_KEVA_DELETE:
+        return false;
+
       default:
         assert(false);
     }
@@ -133,6 +142,9 @@ public:
       case OP_KEVA_PUT:
         return true;
 
+      case OP_KEVA_DELETE:
+        return true;
+
       default:
         assert(false);
     }
@@ -149,6 +161,9 @@ public:
       case OP_KEVA_PUT:
         return args[0];
 
+      case OP_KEVA_DELETE:
+        return args[0];
+
       case OP_KEVA_NAMESPACE:
         return args[0];
 
@@ -184,6 +199,9 @@ public:
       case OP_KEVA_PUT:
         return args[1];
 
+      case OP_KEVA_DELETE:
+        return args[1];
+
       default:
         assert(false);
     }
@@ -206,6 +224,16 @@ public:
     }
   }
 
+  /**
+   * Return the keva operation value.  This call is only valid for
+   * OP_KEVA_PUT.
+   * @return The keva operation's value.
+   */
+  inline bool isDelete() const
+  {
+    return (op == OP_KEVA_DELETE);
+  }
+
   /**
    * Check if the given script is a keva script.  This is a utility method.
    * @param script The script to parse.
@@ -237,6 +265,15 @@ public:
                                 const valtype& key, const valtype& value);
 
 
+  /**
+   * Build a KEVA_DELETE transaction.
+   * @param addr The address script to append.
+   * @param hash The hash to use.
+   * @return The full KEVA_DELETE script.
+   */
+  static CScript buildKevaDelete(const CScript& addr, const valtype& nameSpace, const valtype& key);
+
+
   static CScript replaceKevaNamespace(const CScript& oldScript, const uint256& txId, valtype& kaveNamespace, const CChainParams& params);
 
 };

src/script/script.h

@@ -186,7 +186,7 @@ enum opcodetype
     // Keva
     OP_KEVA_PUT=0xd0,
     OP_KEVA_NAMESPACE=0xd1,
-
+    OP_KEVA_DELETE=0xd2,
 
     // template matching params
     OP_SMALLINTEGER = 0xfa,

src/txmempool.h

@@ -142,6 +142,11 @@ public:
         return kevaOp.isKevaOp() && kevaOp.getKevaOp() == OP_KEVA_PUT;
     }
 
+    inline bool isKeyDelete() const
+    {
+        return kevaOp.isKevaOp() && kevaOp.getKevaOp() == OP_KEVA_DELETE;
+    }
+
     inline const valtype& getNamespace() const
     {
         return kevaOp.getOpNamespace();

src/wallet/rpckeva.cpp

@@ -42,8 +42,8 @@ UniValue keva_namespace(const JSONRPCRequest& request)
         "1. \"display_name\"          (string, required) the display name of the namespace\n"
         "\nResult:\n"
         "[\n"
-        "  xxxxx,   (string) the txid, required for keva_put\n"
+        "  xxxxx,   (string) the txid\n"
-        "  xxxxx,   (string) the unique namespace id, required for keva_put\n"
+        "  xxxxx,   (string) the unique namespace id\n"
         "]\n"
         "\nExamples:\n"
         + HelpExampleCli ("keva_namespace", "\"display name\"")
@@ -96,8 +96,11 @@ UniValue keva_namespace(const JSONRPCRequest& request)
              kevaNamespaceBase58.c_str(), displayNameStr.c_str(), txid.c_str());
 
   UniValue res(UniValue::VARR);
-  res.push_back(txid);
+  UniValue obj(UniValue::VOBJ);
-  res.push_back(kevaNamespaceBase58);
+  obj.pushKV("txid", txid);
+  obj.pushKV("namespaceId", kevaNamespaceBase58);
+  res.push_back(obj);
+
   return res;
 }
 
@@ -207,8 +210,8 @@ UniValue keva_put(const JSONRPCRequest& request)
 
   if (request.fHelp || request.params.size() != 3) {
     throw std::runtime_error (
-        "keva_put \"namespace\" \"key\" \"value\" (\"create_namespace\")\n"
+        "keva_put \"namespace\" \"key\" \"value\"\n"
-        "\nUpdate a name and possibly transfer it.\n"
+        "\nInsert or update a key value pair in the given namespace.\n"
         + HelpRequiringPassphrase (pwallet) +
         "\nArguments:\n"
         "1. \"namespace\"            (string, required) the namespace to insert the key to\n"
@@ -251,7 +254,7 @@ UniValue keva_put(const JSONRPCRequest& request)
   COutput output;
   std::string kevaNamespce = namespaceStr;
   if (!pwallet->FindKevaCoin(output, kevaNamespce)) {
-    throw JSONRPCError (RPC_TRANSACTION_ERROR, "this name can not be updated");
+    throw JSONRPCError (RPC_TRANSACTION_ERROR, "this namespace can not be updated");
   }
   const COutPoint outp(output.tx->GetHash(), output.i);
   const CTxIn txIn(outp);
@@ -281,6 +284,96 @@ UniValue keva_put(const JSONRPCRequest& request)
   return wtx.GetHash().GetHex();
 }
 
+UniValue keva_delete(const JSONRPCRequest& request)
+{
+  CWallet* const pwallet = GetWalletForJSONRPCRequest(request);
+  if (!EnsureWalletIsAvailable (pwallet, request.fHelp)) {
+    return NullUniValue;
+  }
+
+  if (request.fHelp || request.params.size() != 2) {
+    throw std::runtime_error (
+        "keva_delete \"namespace\" \"key\"\n"
+        "\nRemove the specified key from the given namespace.\n"
+        + HelpRequiringPassphrase (pwallet) +
+        "\nArguments:\n"
+        "1. \"namespace\"            (string, required) the namespace to insert the key to\n"
+        "2. \"key\"                  (string, required) value for the key\n"
+        "\nResult:\n"
+        "\"txid\"             (string) the keva_delete's txid\n"
+        "\nExamples:\n"
+        + HelpExampleCli ("keva_delete", "\"mynamespace\", \"key\"")
+      );
+  }
+
+  RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VSTR});
+  RPCTypeCheckArgument(request.params[0], UniValue::VSTR);
+  RPCTypeCheckArgument(request.params[1], UniValue::VSTR);
+
+  ObserveSafeMode ();
+
+  const std::string namespaceStr = request.params[0].get_str();
+  valtype nameSpace;
+  if (!DecodeKevaNamespace(namespaceStr, Params(), nameSpace)) {
+    throw JSONRPCError (RPC_INVALID_PARAMETER, "invalid namespace id");
+  }
+  if (nameSpace.size () > MAX_NAMESPACE_LENGTH) {
+    throw JSONRPCError (RPC_INVALID_PARAMETER, "the namespace is too long");
+  }
+
+  const std::string keyStr = request.params[1].get_str ();
+  const valtype key = ValtypeFromString (keyStr);
+  if (key.size () > MAX_KEY_LENGTH) {
+    throw JSONRPCError (RPC_INVALID_PARAMETER, "the key is too long");
+  }
+
+  CKevaData data;
+  {
+    LOCK2(cs_main, mempool.cs);
+    if (!pcoinsTip->GetName(nameSpace, key, data)) {
+      std::vector<std::tuple<valtype, valtype, valtype, uint256>> unconfirmedKeyValueList;
+      valtype val;
+      if (!mempool.getUnconfirmedKeyValue(nameSpace, key, val) || val.size() == 0) {
+        throw JSONRPCError (RPC_TRANSACTION_ERROR, "key not found");
+      }
+    }
+  }
+
+  EnsureWalletIsUnlocked(pwallet);
+
+  COutput output;
+  std::string kevaNamespce = namespaceStr;
+  if (!pwallet->FindKevaCoin(output, kevaNamespce)) {
+    throw JSONRPCError (RPC_TRANSACTION_ERROR, "this namespace can not be updated");
+  }
+  const COutPoint outp(output.tx->GetHash(), output.i);
+  const CTxIn txIn(outp);
+
+  CReserveKey keyName(pwallet);
+  CPubKey pubKeyReserve;
+  const bool ok = keyName.GetReservedKey(pubKeyReserve, true);
+  assert(ok);
+  bool usedKey = false;
+
+  CScript addrName;
+  usedKey = true;
+  addrName = GetScriptForDestination(pubKeyReserve.GetID());
+
+  const CScript kevaScript = CKevaScript::buildKevaDelete(addrName, nameSpace, key);
+
+  CCoinControl coinControl;
+  CWalletTx wtx;
+  valtype empty;
+  SendMoneyToScript(pwallet, kevaScript, &txIn, empty,
+                     KEVA_LOCKED_AMOUNT, false, wtx, coinControl);
+
+  if (usedKey) {
+    keyName.KeepKey();
+  }
+
+  return wtx.GetHash().GetHex();
+}
+
 UniValue keva_get(const JSONRPCRequest& request)
 {
   CWallet* const pwallet = GetWalletForJSONRPCRequest(request);
@@ -392,6 +485,7 @@ UniValue keva_pending(const JSONRPCRequest& request)
   UniValue arr(UniValue::VARR);
   const std::string opKevaNamepsace = "keva_namespace";
   const std::string opKevaPut       = "keva_put";
+  const std::string opKevaDelete    = "keva_delete";
 
   for (auto entry: unconfirmedNamespaces) {
     UniValue obj(UniValue::VOBJ);
@@ -404,11 +498,19 @@ UniValue keva_pending(const JSONRPCRequest& request)
 
   for (auto entry: unconfirmedKeyValueList) {
     UniValue obj(UniValue::VOBJ);
+    const valtype val = std::get<2>(entry);
+    if (val.size() > 0) {
       obj.pushKV("op", opKevaPut);
       obj.pushKV("namespace", EncodeBase58Check(std::get<0>(entry)));
       obj.pushKV("key", ValtypeToString(std::get<1>(entry)));
       obj.pushKV("value", ValtypeToString(std::get<2>(entry)));
       obj.pushKV("txid", std::get<3>(entry).ToString());
+    } else {
+      obj.pushKV("op", opKevaDelete);
+      obj.pushKV("namespace", EncodeBase58Check(std::get<0>(entry)));
+      obj.pushKV("key", ValtypeToString(std::get<1>(entry)));
+      obj.pushKV("txid", std::get<3>(entry).ToString());
+    }
     arr.push_back(obj);
   }
 

src/wallet/rpcwallet.cpp

@@ -3593,6 +3593,7 @@ extern UniValue rescanblockchain(const JSONRPCRequest& request);
 // in rpckeva.cpp
 extern UniValue keva_namespace(const JSONRPCRequest& request);
 extern UniValue keva_put(const JSONRPCRequest& request);
+extern UniValue keva_delete(const JSONRPCRequest& request);
 extern UniValue keva_get(const JSONRPCRequest& request);
 extern UniValue keva_list_namespaces(const JSONRPCRequest& request);
 extern UniValue keva_pending(const JSONRPCRequest& request);
@@ -3658,6 +3659,7 @@ static const CRPCCommand commands[] =
     { "kevacoin",           "keva_namespace",           &keva_namespace,           {"display_name"} },
     { "kevacoin",           "keva_list_namespaces",     &keva_list_namespaces,     {} },
     { "kevacoin",           "keva_put",                 &keva_put,                 {"namespace", "key", "value"} },
+    { "kevacoin",           "keva_delete",              &keva_delete,              {"namespace", "key"} },
     { "kevacoin",           "keva_get",                 &keva_get,                 {"namespace", "key"} },
     { "kevacoin",           "keva_pending",             &keva_pending,             {"namespace"} }
 };