Basic functionality for direct RPC for StorageAPI communication

This has several advantages:
* Completely bypasses all MessageBus indirections
* Explicit setup of RPC thread pool
* Direct dispatch from RPC thread to persistence queue pool
* Better control of encoding/decoding and buffer usage

3 files changed, 16 insertions, 15 deletions

diff --git a/storageapi/src/vespa/storageapi/mbusprot/protocolserialization7.h b/storageapi/src/vespa/storageapi/mbusprot/protocolserialization7.h
index f3499150278..d29167031a4 100644
--- a/storageapi/src/vespa/storageapi/mbusprot/protocolserialization7.h
+++ b/storageapi/src/vespa/storageapi/mbusprot/protocolserialization7.h
@@ -5,8 +5,7 @@
 #include "protocolserialization.h"
 #include <vespa/documentapi/loadtypes/loadtypeset.h>
 
-namespace storage {
-namespace mbusprot {
+namespace storage::mbusprot {
 
 /**
  * Protocol serialization version that uses Protocol Buffers for all its binary
@@ -143,4 +142,3 @@ private:
 };
 
 }
-}
diff --git a/storageapi/src/vespa/storageapi/mbusprot/storagecommand.h b/storageapi/src/vespa/storageapi/mbusprot/storagecommand.h
index 26c9ef00752..ef1d5082a04 100644
--- a/storageapi/src/vespa/storageapi/mbusprot/storagecommand.h
+++ b/storageapi/src/vespa/storageapi/mbusprot/storagecommand.h
@@ -12,7 +12,7 @@ class StorageCommand : public mbus::Message, public StorageMessage {
 public:
     typedef std::unique_ptr<StorageCommand> UP;
 
-    StorageCommand(api::StorageCommand::SP);
+    explicit StorageCommand(api::StorageCommand::SP);
 
     const mbus::string & getProtocol() const override { return StorageProtocol::NAME; }
     uint32_t getType() const override { return _cmd->getType().getId(); }
@@ -21,6 +21,9 @@ public:
     api::StorageMessage::SP getInternalMessage() override { return _cmd; }
     api::StorageMessage::CSP getInternalMessage() const override { return _cmd; }
 
+    bool has_command() const noexcept { return (_cmd.get() != nullptr); }
+    api::StorageCommand::SP steal_command() { return std::move(_cmd); }
+
     bool hasBucketSequence() const override { return false; }
 
     uint8_t priority() const override {
diff --git a/storageapi/src/vespa/storageapi/messageapi/storagemessage.cpp b/storageapi/src/vespa/storageapi/messageapi/storagemessage.cpp
index 93030f699cc..d1bd24f5087 100644
--- a/storageapi/src/vespa/storageapi/messageapi/storagemessage.cpp
+++ b/storageapi/src/vespa/storageapi/messageapi/storagemessage.cpp
@@ -105,7 +105,7 @@ const MessageType MessageType::SETBUCKETSTATE_REPLY("SetBucketStateReply", SETBU
 const MessageType&
 MessageType::MessageType::get(Id id)
 {
-    std::map<Id, MessageType*>::const_iterator it = _codes.find(id);
+    auto it = _codes.find(id);
     if (it == _codes.end()) {
         std::ostringstream ost;
         ost << "No message type with id " << id << ".";
@@ -115,13 +115,13 @@ MessageType::MessageType::get(Id id)
 }
 MessageType::MessageType(vespalib::stringref name, Id id,
                          const MessageType* replyOf)
-    : _name(name), _id(id), _reply(NULL), _replyOf(replyOf)
+    : _name(name), _id(id), _reply(nullptr), _replyOf(replyOf)
 {
     _codes[id] = this;
-    if (_replyOf != 0) {
-        assert(_replyOf->_reply == 0);
+    if (_replyOf) {
+        assert(_replyOf->_reply == nullptr);
         // Ugly cast to let initialization work
-        MessageType& type = const_cast<MessageType&>(*_replyOf);
+        auto& type = const_cast<MessageType&>(*_replyOf);
         type._reply = this;
     }
 }
@@ -144,7 +144,7 @@ StorageMessageAddress::StorageMessageAddress(const mbus::Route& route)
       _retryEnabled(false),
       _protocol(DOCUMENT),
       _cluster(""),
-      _type(0),
+      _type(nullptr),
       _index(0xFFFF)
 { }
 
@@ -179,7 +179,7 @@ StorageMessageAddress::~StorageMessageAddress() = default;
 uint16_t
 StorageMessageAddress::getIndex() const
 {
-    if (_type == 0) {
+    if (!_type) {
         throw vespalib::IllegalStateException("Cannot retrieve node index out of external address", VESPA_STRLOC);
     }
     return _index;
@@ -188,7 +188,7 @@ StorageMessageAddress::getIndex() const
 const lib::NodeType&
 StorageMessageAddress::getNodeType() const
 {
-    if (_type == 0) {
+    if (!_type) {
         throw vespalib::IllegalStateException("Cannot retrieve node type out of external address", VESPA_STRLOC);
     }
     return *_type;
@@ -197,7 +197,7 @@ StorageMessageAddress::getNodeType() const
 const vespalib::string&
 StorageMessageAddress::getCluster() const
 {
-    if (_type == 0) {
+    if (!_type) {
         throw vespalib::IllegalStateException("Cannot retrieve cluster out of external address", VESPA_STRLOC);
     }
     return _cluster;
@@ -209,7 +209,7 @@ StorageMessageAddress::operator==(const StorageMessageAddress& other) const
     if (_protocol != other._protocol) return false;
     if (_retryEnabled != other._retryEnabled) return false;
     if (_type != other._type) return false;
-    if (_type != 0) {
+    if (_type) {
         if (_cluster != other._cluster) return false;
         if (_index != other._index) return false;
         if (_type != other._type) return false;
@@ -237,7 +237,7 @@ StorageMessageAddress::print(vespalib::asciistream & out) const
     if (_retryEnabled) {
         out << ", retry enabled";
     }
-    if (_type == 0) {
+    if (!_type) {
         out << ", " << _route.toString() << ")";
     } else {
         out << ", cluster " << _cluster << ", nodetype " << *_type