hush3/doc/developer-notes.md

Testing a Branch

To test a branch called zindexdb with a fresh clone

git clone https://git.hush.is/hush/hush3 hush3-testing
cd hush3-testing
git checkout zindexdb
# you need 2GB RAM free per -jN
./build.sh -j2; make; make; make # this deals with build-system race condition bugs

# we want to test a fresh sync, so backup current data
TIME=`perl -e "print time"`
mv ~/.komodo/{HUSH3,HUSH3-backup-$TIME}
mkdir ~/.komodo/HUSH3

# Use your previous config as a base
cp ~/.komodo/{HUSH3-backup-$TIME,HUSH3}/HUSH3.conf
# Add zindex to your node
echo "zindex=1" >> ~/.komodo/HUSH3/HUSH3.conf


# This is optional but will likely speed up sync time greatly
cp ~/.komodo/{HUSH3-backup,HUSH3}/peers.dat

# This log file is helpful for debugging more and will contain a history of the
# size of the anonset at every block height
./src/hushd &> hushd.log &
# to look at the log
tail -f hushd.log

To get a CSV file of the value of the anonset size for every block height:

grep 'setting zstats' hushd.log | cut -d= -f2

This only needs to be calculated once, if we can verify it's correct. These are historical values that do not change. These values should match on all nodes:

46913,2547,2253,294
46914,2549,2254,295
46915,2549,2254,295
46916,2553,2257,296
46917,2553,2257,296

We should also check a recent block height to verify it's working correctly. The big "test" for this zindexdb branch is:

• If you stop a node, and restart, are the stats from getchaintxtstats correct, i.e. the anonset stats? For instance, shielded_pool_size should be close to 500000, if it's close to or exactly 0, something is wrong.
• Is there a new file called zindex.dat in ~/.komodo/HUSH3/ ?
• Is zindex.dat 149 bytes ?

Coding

Various coding styles have been used during the history of the codebase, and the result is not very consistent. However, we're now trying to converge to a single style, so please use it in new code. Old code will be converted gradually.

• Basic rules specified in src/.clang-format. Use a recent clang-format-3.5 to format automatically.
  • Braces on new lines for namespaces, classes, functions, methods.
  • Braces on the same line for everything else.
  • 4 space indentation (no tabs) for every block except namespaces.
  • No indentation for public/protected/private or for namespaces.
  • No extra spaces inside parenthesis; don't do ( this )
  • No space after function names; one space after if, for and while.

Block style example:

namespace foo
{
class Class
{
    bool Function(char* psz, int n)
    {
        // Comment summarising what this section of code does
        for (int i = 0; i < n; i++) {
            // When something fails, return early
            if (!Something())
                return false;
            ...
        }

        // Success return is usually at the end
        return true;
    }
}
}

Development tips and tricks

compiling for debugging

Run configure with the --enable-debug option, then make. Or run configure with CXXFLAGS="-g -ggdb -O0" or whatever debug flags you need.

debug.log

If the code is behaving strangely, take a look in the debug.log file in the data directory; error and debugging messages are written there.

The -debug=... command-line option controls debugging; running with just -debug or -debug=1 will turn on all categories (and give you a very large debug.log file).

testnet and regtest modes

Run with the -testnet option to run with "play zcash" on the test network, if you are testing multi-machine code that needs to operate across the internet.

If you are testing something that can run on one machine, run with the -regtest option. In regression test mode, blocks can be created on-demand; see qa/rpc-tests/ for tests that run in -regtest mode.

DEBUG_LOCKORDER

Hush is a multithreaded application, and deadlocks or other multithreading bugs can be very difficult to track down. Compiling with -DDEBUG_LOCKORDER (configure CXXFLAGS="-DDEBUG_LOCKORDER -g") inserts run-time checks to keep track of which locks are held, and adds warnings to the debug.log file if inconsistencies are detected.

Locking/mutex usage notes

The code is multi-threaded, and uses mutexes and the LOCK/TRY_LOCK macros to protect data structures.

Deadlocks due to inconsistent lock ordering (thread 1 locks cs_main and then cs_wallet, while thread 2 locks them in the opposite order: result, deadlock as each waits for the other to release its lock) are a problem. Compile with -DDEBUG_LOCKORDER to get lock order inconsistencies reported in the debug.log file.

Re-architecting the core code so there are better-defined interfaces between the various components is a goal, with any necessary locking done by the components (e.g. see the self-contained CKeyStore class and its cs_KeyStore lock for example).

Threads

• ThreadScriptCheck : Verifies block scripts.

• ThreadImport : Loads blocks from blk*.dat files or bootstrap.dat.

• StartNode : Starts other threads.

• ThreadDNSAddressSeed : Loads addresses of peers from the DNS.

• ThreadMapPort : Universal plug-and-play startup/shutdown

• ThreadSocketHandler : Sends/Receives data from peers on port 8233.

• ThreadOpenAddedConnections : Opens network connections to added nodes.

• ThreadOpenConnections : Initiates new connections to peers.

• ThreadMessageHandler : Higher-level message handling (sending and receiving).

• DumpAddresses : Dumps IP addresses of nodes to peers.dat.

• ThreadFlushWalletDB : Close the wallet.dat file if it hasn't been used in 500ms.

• ThreadRPCServer : Remote procedure call handler, listens on port 8232 for connections and services them.

• HushMiner : Generates zcash (if wallet is enabled).

• Shutdown : Does an orderly shutdown of everything.

Pull Request Terminology

Concept ACK - Agree with the idea and overall direction, but have neither reviewed nor tested the code changes.

utACK (untested ACK) - Reviewed and agree with the code changes but haven't actually tested them.

Tested ACK - Reviewed the code changes and have verified the functionality or bug fix.

ACK - A loose ACK can be confusing. It's best to avoid them unless it's a documentation/comment only change in which case there is nothing to test/verify; therefore the tested/untested distinction is not there.

NACK - Disagree with the code changes/concept. Should be accompanied by an explanation.