[Ethereum] How does CryptoKitties track time

dappsoraclestimerstimestamp

I'm looking at KittyBreeding.sol and see

 /// @dev Set the cooldownEndTime for the given Kitty, based on its current cooldownIndex.
    ///  Also increments the cooldownIndex (unless it has hit the cap).
    /// @param _kitten A reference to the Kitty in storage which needs its timer started.
    function _triggerCooldown(Kitty storage _kitten) internal {
        // Compute the end of the cooldown time (based on current cooldownIndex)
        _kitten.cooldownEndTime = uint64(now + cooldowns[_kitten.cooldownIndex]);

but I don't see where "now" is defined, except in their kitty-core.test.js

How does this DAPP track time, which lets the website show timers?

Best Answer

now is a Solidity special variable, which equates to the current time since the epoch, in seconds.

From the documentation (linked above):

now (uint): current block timestamp (alias for block.timestamp)

Related Solutions

[Ethereum] How does Ethereum regulate the time between blocks

If you are using geth here's a patch that I use to accelerate mining. You could probably modify it to decelerate mining if you wish. (I'm curious why you wish to go slower). In any event, I think the answer to "how does the interval for mining get set" is "not very clear from the code"... but this patch should give you a head start in understanding the timing of geth.

diff --git a/eth/fetcher/fetcher.go b/eth/fetcher/fetcher.go
index d88d919..f03fd30 100644
--- a/eth/fetcher/fetcher.go
+++ b/eth/fetcher/fetcher.go
@@ -34,7 +34,7 @@ import (
 const (
    arriveTimeout = 500 * time.Millisecond // Time allowance before an announced block is explicitlrd
    gatherSlack   = 100 * time.Millisecond // Interval used to collate almost-expired announces witfs
-   fetchTimeout  = 5 * time.Second        // Maximum alloted time to return an explicitly requestebk
+   fetchTimeout  = 1 * time.Second        // Maximum alloted time to return an explicitly requestebk
    maxUncleDist  = 7                      // Maximum allowed backward distance from the chain head
    maxQueueDist  = 32                     // Maximum allowed distance from the chain head to queue
    hashLimit     = 256                    // Maximum number of unique blocks a peer may have annoued
diff --git a/eth/peer.go b/eth/peer.go
index 15ba22f..0201057 100644
--- a/eth/peer.go
+++ b/eth/peer.go
@@ -41,7 +41,7 @@ var (
 const (
    maxKnownTxs      = 32768 // Maximum transactions hashes to keep in the known list (prevent DOS)
    maxKnownBlocks   = 1024  // Maximum block hashes to keep in the known list (prevent DOS)
-   handshakeTimeout = 5 * time.Second
+   handshakeTimeout = 1 * time.Second
 )

 // PeerInfo represents a short summary of the Ethereum sub-protocol metadata known
diff --git a/miner/worker.go b/miner/worker.go
index 754a6fc..2b62b59 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -466,7 +466,7 @@ func (self *worker) commitNewWork() {
            tstamp = parent.Time().Int64() + 1
    }
    // this will ensure we're not going off too far in the future
-   if now := time.Now().Unix(); tstamp > now+4 {
+   if now := time.Now().Unix(); tstamp > now {
            wait := time.Duration(tstamp-now) * time.Second
            glog.V(logger.Info).Infoln("We are too far in the future. Waiting for", wait)
            time.Sleep(wait)
diff --git a/p2p/rlpx.go b/p2p/rlpx.go
index aaa7338..ce82eb7 100644
--- a/p2p/rlpx.go
+++ b/p2p/rlpx.go
@@ -57,7 +57,7 @@ const (

    // total timeout for encryption handshake and protocol
    // handshake in both directions.
-   handshakeTimeout = 5 * time.Second
+   handshakeTimeout = 2 * time.Second

    // This is the timeout for sending the disconnect reason.
    // This is shorter than the usual timeout because we don't want
diff --git a/params/protocol_params.go b/params/protocol_params.go
index dcc17e0..21a49c5 100755
--- a/params/protocol_params.go
+++ b/params/protocol_params.go
@@ -29,10 +29,10 @@ var (
    CallNewAccountGas      = big.NewInt(25000)  // Paid for CALL when the destination address didn'e.
    TxGas                  = big.NewInt(21000)  // Per transaction. NOTE: Not payable on data of cas.
    TxDataZeroGas          = big.NewInt(4)      // Per byte of data attached to a transaction that u.
-   DifficultyBoundDivisor = big.NewInt(2048)   // The bound divisor of the difficulty, used in thep.
+   DifficultyBoundDivisor = big.NewInt(1)      // The bound divisor of the difficulty, used in thep.
    QuadCoeffDiv           = big.NewInt(512)    // Divisor for the quadratic particle of the memoryo.
-   GenesisDifficulty      = big.NewInt(131072) // Difficulty of the Genesis block.
-   DurationLimit          = big.NewInt(13)     // The decision boundary on the blocktime duration e.
+   GenesisDifficulty      = big.NewInt(1)      // Difficulty of the Genesis block.
+   DurationLimit          = big.NewInt(1)      // The decision boundary on the blocktime duration e.
    SstoreSetGas           = big.NewInt(20000)  // Once per SLOAD operation.
    LogDataGas             = big.NewInt(8)      // Per byte in a LOG* operation's data.
    CallStipend            = big.NewInt(2300)   // Free gas given at beginning of call.
@@ -57,7 +57,7 @@ var (
    CreateDataGas        = big.NewInt(200)    //
    Ripemd160Gas         = big.NewInt(600)    //
    Ripemd160WordGas     = big.NewInt(120)    //
-   MinimumDifficulty    = big.NewInt(131072) // The minimum that the difficulty may ever be.
+   MinimumDifficulty    = big.NewInt(1)      // The minimum that the difficulty may ever be.
    CallCreateDepth      = big.NewInt(1024)   // Maximum depth of call/create stack.
    ExpGas               = big.NewInt(10)     // Once per EXP instuction.
    LogGas               = big.NewInt(375)    // Per LOG* operation.

[Ethereum] Is block.timestamp safe for longer time periods

Yes, you can guarantee long run time accuracy. Miners can't cheat that much to change the timestamp over days. Blocktime is adjusted to be constant within certain error margins, and timestamps is guaranteed to be rejected if they are excessive. Serenity and PoS 'proven' until core team decides otherwise. It is very very unlikely to happen, what reason could they possibly have? Its a feature not a bug.

Best Answer

Related Solutions

[Ethereum] How does Ethereum regulate the time between blocks

[Ethereum] Is block.timestamp safe for longer time periods

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