allow VP with no fee

backend/src/event-handlers/validation-pools.js

@@ -50,17 +50,25 @@ const start = async () => {
     const decisions = await Promise.mapSeries(deciders, (decider) => decider(pool, post));
     const inFavor = decisions.some((x) => x === true);
     const nullResult = decisions.some((x) => x === null);
+    const currentRep = await dao.balanceOf(await wallet.getAddress());
+    let stakeAmount = currentRep;
     if (!inFavor && nullResult) {
-      console.log(`Obtained a NULL RESULT for pool ${poolIndex}. Abstaining from the vote.`);
+      console.log(`Obtained a NULL RESULT for pool ${poolIndex}.`);
       // TODO: Retry?
       // TODO: Notify
-      return;
+      // Calculate the minimum stake S against the post, such that if the honest actors
+      // each stake S, the result will be enough to meet the win ratio.
+      // This way, we combat the threat of a truly invalid post,
+      // while reducing our exposure in the case that the error is unique to us.
+      // Assume 2/3 honest actors.
+      // S * (2/3) = 1/3
+      // S = 1/2;
+      stakeAmount = Math.ceil(currentRep / 2);
     }
     // Stake all available reputation
-    const currentRep = await dao.balanceOf(await wallet.getAddress());
-    console.log(`STAKING ${currentRep} ${inFavor ? 'in favor of' : 'against'} pool ${poolIndex}`);
+    console.log(`STAKING ${stakeAmount} ${inFavor ? 'in favor of' : 'against'} pool ${poolIndex}`);
     try {
-      await dao.stakeOnValidationPool(poolIndex, currentRep, inFavor);
+      await dao.stakeOnValidationPool(poolIndex, stakeAmount, inFavor);
     } catch (e) {
       // Maybe the end time passed?
       console.error(`STAKING failed, reason: ${e.reason}`);

ethereum/contracts/Rollup.sol

@@ -121,6 +121,7 @@ contract Rollup is Availability {
 
     /// If the batch worker fails to submit the batch, a new batch worker may be selected
     function resetBatchWorker() public {
+        // TODO: Grace period after the current batch is due and before the worker can be replaced
         require(
             block.timestamp - batchStart > batchInterval,
             "Current batch interval has not yet elapsed"
@@ -131,7 +132,8 @@ contract Rollup is Availability {
                 block.timestamp - lastWorkerReset >= minResetInterval,
             "Mininum reset interval has not elapsed since last batch worker reset"
         );
-        // TODO: Should the current batch worker's availability stakes be forfeit?
+        // TODO: Submit a validation pool targeting a null post, and send the worker's availability stake
+        // This gives the DAO an opportunity to police the failed work
         // Select a new batch worker
         batchWorkerStakeIndex = assignWork();
         batchWorker = stakes[batchWorkerStakeIndex].worker;

ethereum/contracts/core/Bench.sol

@@ -97,7 +97,6 @@ contract Bench {
             msg.sender == address(dao),
             "Only DAO contract may call initiateValidationPool"
         );
-        require(msg.value > 0, "Fee is required to initiate validation pool");
         require(duration >= minDuration, "Duration is too short");
         require(duration <= maxDuration, "Duration is too long");
         require(
@@ -124,7 +123,7 @@ contract Bench {
         // We use our privilege as the DAO contract to mint reputation in proportion with the fee.
         // Here we assume a minting ratio of 1
         // TODO: Make minting ratio an adjustable parameter
-        dao.mint(address(dao), msg.value);
+        dao.mint(address(dao), pool.props.fee);
         pool.props.minted = msg.value;
         dao.emitValidationPoolInitiated(poolIndex);
     }

ethereum/test/ValidationPools.js

@@ -52,9 +52,9 @@ describe('Validation Pools', () => {
   });
 
   describe('Initiate', () => {
-    it('should not be able to initiate a validation pool without a fee', async () => {
+    it('should be able to initiate a validation pool without a fee', async () => {
       const init = () => initiateValidationPool({ fee: 0 });
-      await expect(init()).to.be.revertedWith('Fee is required to initiate validation pool');
+      await expect(init()).to.emit(dao, 'ValidationPoolInitiated');
     });
 
     it('should not be able to initiate a validation pool with a quorum below the minimum', async () => {