[marketplace] Reward is paid out per second per slot

contracts/Marketplace.sol

@@ -39,9 +39,10 @@ contract Marketplace is Collateral, Proofs {
 
     _createLock(id, request.expiry);
 
-    funds.received += request.ask.reward;
-    funds.balance += request.ask.reward;
-    transferFrom(msg.sender, request.ask.reward);
+    uint256 amount = price(request);
+    funds.received += amount;
+    funds.balance += amount;
+    transferFrom(msg.sender, amount);
 
     emit StorageRequested(id, request.ask);
   }
@@ -84,7 +85,7 @@ contract Marketplace is Collateral, Proofs {
     Slot storage slot = slots[slotId];
     require(slot.host != address(0), "Slot empty");
     require(!slot.hostPaid, "Already paid");
-    uint256 amount = requests[requestId].ask.reward;
+    uint256 amount = pricePerSlot(requests[requestId]);
     funds.sent += amount;
     funds.balance -= amount;
     slot.hostPaid = true;
@@ -111,6 +112,14 @@ contract Marketplace is Collateral, Proofs {
     return _end(contractId);
   }
 
+  function price(Request calldata request) private pure returns (uint256) {
+    return request.ask.slots * request.ask.duration * request.ask.reward;
+  }
+
+  function pricePerSlot(Request memory request) private pure returns (uint256) {
+    return request.ask.duration * request.ask.reward;
+  }
+
   struct Request {
     address client;
     Ask ask;
@@ -123,7 +132,7 @@ contract Marketplace is Collateral, Proofs {
     uint256 size; // size of requested storage in number of bytes
     uint256 duration; // how long content should be stored (in seconds)
     uint256 proofProbability; // how often storage proofs are required
-    uint256 reward; // reward that the client will pay (in number of tokens)
+    uint256 reward; // amount of tokens paid per second per slot to hosts
     uint64 slots; // the total number of hosts that store the data set
   }
 

test/Marketplace.test.js

@@ -4,6 +4,7 @@ const { expect } = require("chai")
 const { exampleRequest } = require("./examples")
 const { now, hours } = require("./time")
 const { requestId, slotId, askToArray } = require("./ids")
+const { price, pricePerSlot } = require("./price")
 const {
   snapshot,
   revert,
@@ -33,7 +34,7 @@ describe("Marketplace", function () {
     const TestToken = await ethers.getContractFactory("TestToken")
     token = await TestToken.deploy()
     for (account of [client, host1, host2, host3]) {
-      await token.mint(account.address, 1000)
+      await token.mint(account.address, 1_000_000_000)
     }
 
     const Marketplace = await ethers.getContractFactory("Marketplace")
@@ -69,7 +70,7 @@ describe("Marketplace", function () {
     })
 
     it("emits event when storage is requested", async function () {
-      await token.approve(marketplace.address, request.ask.reward)
+      await token.approve(marketplace.address, price(request))
       await expect(marketplace.requestStorage(request))
         .to.emit(marketplace, "StorageRequested")
         .withArgs(requestId(request), askToArray(request.ask))
@@ -77,14 +78,14 @@ describe("Marketplace", function () {
 
     it("rejects request with invalid client address", async function () {
       let invalid = { ...request, client: host.address }
-      await token.approve(marketplace.address, invalid.ask.reward)
+      await token.approve(marketplace.address, price(invalid))
       await expect(marketplace.requestStorage(invalid)).to.be.revertedWith(
         "Invalid client address"
       )
     })
 
     it("rejects request with insufficient payment", async function () {
-      let insufficient = request.ask.reward - 1
+      let insufficient = price(request) - 1
       await token.approve(marketplace.address, insufficient)
       await expect(marketplace.requestStorage(request)).to.be.revertedWith(
         "ERC20: insufficient allowance"
@@ -92,7 +93,7 @@ describe("Marketplace", function () {
     })
 
     it("rejects resubmission of request", async function () {
-      await token.approve(marketplace.address, request.ask.reward * 2)
+      await token.approve(marketplace.address, price(request) * 2)
       await marketplace.requestStorage(request)
       await expect(marketplace.requestStorage(request)).to.be.revertedWith(
         "Request already exists"
@@ -103,7 +104,7 @@ describe("Marketplace", function () {
   describe("filling a slot", function () {
     beforeEach(async function () {
       switchAccount(client)
-      await token.approve(marketplace.address, request.ask.reward)
+      await token.approve(marketplace.address, price(request))
       await marketplace.requestStorage(request)
       switchAccount(host)
       await token.approve(marketplace.address, collateral)
@@ -160,7 +161,7 @@ describe("Marketplace", function () {
     it("is rejected when request is expired", async function () {
       switchAccount(client)
       let expired = { ...request, expiry: now() - hours(1) }
-      await token.approve(marketplace.address, request.ask.reward)
+      await token.approve(marketplace.address, price(request))
       await marketplace.requestStorage(expired)
       switchAccount(host)
       await expect(
@@ -179,7 +180,7 @@ describe("Marketplace", function () {
   describe("paying out a slot", function () {
     beforeEach(async function () {
       switchAccount(client)
-      await token.approve(marketplace.address, request.ask.reward)
+      await token.approve(marketplace.address, price(request))
       await marketplace.requestStorage(request)
       switchAccount(host)
       await token.approve(marketplace.address, collateral)
@@ -197,7 +198,7 @@ describe("Marketplace", function () {
       const startBalance = await token.balanceOf(host.address)
       await marketplace.payoutSlot(slot.request, slot.index)
       const endBalance = await token.balanceOf(host.address)
-      expect(endBalance - startBalance).to.equal(request.ask.reward)
+      expect(endBalance - startBalance).to.equal(pricePerSlot(request))
     })
 
     it("is only allowed when the slot is filled", async function () {
@@ -234,7 +235,7 @@ describe("Marketplace", function () {
   describe("fulfilling a request", function () {
     beforeEach(async function () {
       switchAccount(client)
-      await token.approve(marketplace.address, request.ask.reward)
+      await token.approve(marketplace.address, price(request))
       await marketplace.requestStorage(request)
       switchAccount(host)
       await token.approve(marketplace.address, collateral)

test/Storage.test.js

@@ -6,6 +6,7 @@ const { exampleRequest } = require("./examples")
 const { advanceTime, advanceTimeTo, currentTime } = require("./evm")
 const { requestId, slotId } = require("./ids")
 const { periodic } = require("./time")
+const { price } = require("./price")
 
 describe("Storage", function () {
   const proof = hexlify(randomBytes(42))
@@ -29,8 +30,8 @@ describe("Storage", function () {
     token = await ethers.getContract("TestToken")
     storage = await ethers.getContract("Storage")
 
-    await token.mint(client.address, 1000)
-    await token.mint(host.address, 1000)
+    await token.mint(client.address, 1_000_000_000)
+    await token.mint(host.address, 1_000_000_000)
 
     collateralAmount = await storage.collateralAmount()
     slashMisses = await storage.slashMisses()
@@ -44,7 +45,7 @@ describe("Storage", function () {
     }
 
     switchAccount(client)
-    await token.approve(storage.address, request.ask.reward)
+    await token.approve(storage.address, price(request))
     await storage.requestStorage(request)
     switchAccount(host)
     await token.approve(storage.address, collateralAmount)

test/price.js

@@ -0,0 +1,9 @@
+function price(request) {
+  return request.ask.slots * pricePerSlot(request)
+}
+
+function pricePerSlot(request) {
+  return request.ask.duration * request.ask.reward
+}
+
+module.exports = { price, pricePerSlot }