How does NOW work?












8















Say a contract has a condition based on NOW being after a time. Is NOW UTC, and is this validated by each node before being added to the chain? Let's say you want ensure a function is called during a 1 hour window, will this be possible to enforce?



For example:



current stack state: NOW - 15 minutes :: NOW + 45 minutes //pseudocode

code: NOW; SUB; GT; SWAP;

      NOW; SWAP; SUB;

      AND;

      IF { send transaction... } { FAIL; };


This should check that it's greater than NOW - 15 minutes and less than NOW + 45 minutes, which are both true so it can execute the transaction.



It might also be important to understand how the network gets consensus on a block time across the network?






michelson







share|improve this question



























    8















    Say a contract has a condition based on NOW being after a time. Is NOW UTC, and is this validated by each node before being added to the chain? Let's say you want ensure a function is called during a 1 hour window, will this be possible to enforce?



    For example:



    current stack state: NOW - 15 minutes :: NOW + 45 minutes //pseudocode
    
code: NOW; SUB; GT; SWAP;
    
      NOW; SWAP; SUB;
    
      AND;
    
      IF { send transaction... } { FAIL; };


    This should check that it's greater than NOW - 15 minutes and less than NOW + 45 minutes, which are both true so it can execute the transaction.



    It might also be important to understand how the network gets consensus on a block time across the network?






    michelson







    share|improve this question

























      8












      8








      8


      1






      Say a contract has a condition based on NOW being after a time. Is NOW UTC, and is this validated by each node before being added to the chain? Let's say you want ensure a function is called during a 1 hour window, will this be possible to enforce?



      For example:



      current stack state: NOW - 15 minutes :: NOW + 45 minutes //pseudocode
      
code: NOW; SUB; GT; SWAP;
      
      NOW; SWAP; SUB;
      
      AND;
      
      IF { send transaction... } { FAIL; };


      This should check that it's greater than NOW - 15 minutes and less than NOW + 45 minutes, which are both true so it can execute the transaction.



      It might also be important to understand how the network gets consensus on a block time across the network?






      michelson







      share|improve this question














      Say a contract has a condition based on NOW being after a time. Is NOW UTC, and is this validated by each node before being added to the chain? Let's say you want ensure a function is called during a 1 hour window, will this be possible to enforce?



      For example:



      current stack state: NOW - 15 minutes :: NOW + 45 minutes //pseudocode
      
code: NOW; SUB; GT; SWAP;
      
      NOW; SWAP; SUB;
      
      AND;
      
      IF { send transaction... } { FAIL; };


      This should check that it's greater than NOW - 15 minutes and less than NOW + 45 minutes, which are both true so it can execute the transaction.



      It might also be important to understand how the network gets consensus on a block time across the network?






      michelson




      michelson






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 19 hours ago









      RobRob

      2835




      2835






















          3 Answers
          3






          active

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          4














          There is an assumption that all Tezos nodes are synchronized, otherwise the consensus with 1-minute slots would not work. Of course, some delay is ok, but more than a few seconds might prevent a baker from baking.



          NOW is the time at which the block, containing the transaction, should be baked. So, the baker knows the last block time, he knows his slot, so he can compute the time at which he should bake the block. It then uses that time to execute the transactions.






          share|improve this answer































            2














            Nodes time being synchronized is only part of the picture: bakers can always be offline for their own reasons, the network can be stalled, many other transactions could be competing to get selected by bakers, etc. so people need to be very cautious and give plenty of time for an event to occur.



            I would say that a few minutes or even hours is not enough today.
            Is one day enough ? I would tend to think so but I'm not even certain.






            share|improve this answer
























            • If I'm experimenting with building something that can hit milestones during smaller ranges. Kind of curious how close those milestones can be.

              – Rob
              9 hours ago






            • 2





              Understood but let's all remember Fomo3d medium.com/coinmonks/… on Ethereum before requiring milestones too fast.

              – FFF
              9 hours ago



















            2














            The baker chooses the value of NOW. I am aware of these two constraints:



            The protocol enforces that the timestamp is at least the minimal timestamp at which the baker was supposed to bake (some delay after the previous block's timestamp): baking.ml.



            The shell will also ignore a block whose timestamp is too far in the future (more than 15s) relative to the system clock: distributed_db.ml.






            share|improve this answer























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              3 Answers
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              3 Answers
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              active

              oldest

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              active

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              votes






              active

              oldest

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              4














              There is an assumption that all Tezos nodes are synchronized, otherwise the consensus with 1-minute slots would not work. Of course, some delay is ok, but more than a few seconds might prevent a baker from baking.



              NOW is the time at which the block, containing the transaction, should be baked. So, the baker knows the last block time, he knows his slot, so he can compute the time at which he should bake the block. It then uses that time to execute the transactions.






              share|improve this answer




























                4














                There is an assumption that all Tezos nodes are synchronized, otherwise the consensus with 1-minute slots would not work. Of course, some delay is ok, but more than a few seconds might prevent a baker from baking.



                NOW is the time at which the block, containing the transaction, should be baked. So, the baker knows the last block time, he knows his slot, so he can compute the time at which he should bake the block. It then uses that time to execute the transactions.






                share|improve this answer


























                  4












                  4








                  4







                  There is an assumption that all Tezos nodes are synchronized, otherwise the consensus with 1-minute slots would not work. Of course, some delay is ok, but more than a few seconds might prevent a baker from baking.



                  NOW is the time at which the block, containing the transaction, should be baked. So, the baker knows the last block time, he knows his slot, so he can compute the time at which he should bake the block. It then uses that time to execute the transactions.






                  share|improve this answer













                  There is an assumption that all Tezos nodes are synchronized, otherwise the consensus with 1-minute slots would not work. Of course, some delay is ok, but more than a few seconds might prevent a baker from baking.



                  NOW is the time at which the block, containing the transaction, should be baked. So, the baker knows the last block time, he knows his slot, so he can compute the time at which he should bake the block. It then uses that time to execute the transactions.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 13 hours ago









                  lefessanlefessan

                  2,557522




                  2,557522























                      2














                      Nodes time being synchronized is only part of the picture: bakers can always be offline for their own reasons, the network can be stalled, many other transactions could be competing to get selected by bakers, etc. so people need to be very cautious and give plenty of time for an event to occur.



                      I would say that a few minutes or even hours is not enough today.
                      Is one day enough ? I would tend to think so but I'm not even certain.






                      share|improve this answer
























                      • If I'm experimenting with building something that can hit milestones during smaller ranges. Kind of curious how close those milestones can be.

                        – Rob
                        9 hours ago






                      • 2





                        Understood but let's all remember Fomo3d medium.com/coinmonks/… on Ethereum before requiring milestones too fast.

                        – FFF
                        9 hours ago
















                      2














                      Nodes time being synchronized is only part of the picture: bakers can always be offline for their own reasons, the network can be stalled, many other transactions could be competing to get selected by bakers, etc. so people need to be very cautious and give plenty of time for an event to occur.



                      I would say that a few minutes or even hours is not enough today.
                      Is one day enough ? I would tend to think so but I'm not even certain.






                      share|improve this answer
























                      • If I'm experimenting with building something that can hit milestones during smaller ranges. Kind of curious how close those milestones can be.

                        – Rob
                        9 hours ago






                      • 2





                        Understood but let's all remember Fomo3d medium.com/coinmonks/… on Ethereum before requiring milestones too fast.

                        – FFF
                        9 hours ago














                      2












                      2








                      2







                      Nodes time being synchronized is only part of the picture: bakers can always be offline for their own reasons, the network can be stalled, many other transactions could be competing to get selected by bakers, etc. so people need to be very cautious and give plenty of time for an event to occur.



                      I would say that a few minutes or even hours is not enough today.
                      Is one day enough ? I would tend to think so but I'm not even certain.






                      share|improve this answer













                      Nodes time being synchronized is only part of the picture: bakers can always be offline for their own reasons, the network can be stalled, many other transactions could be competing to get selected by bakers, etc. so people need to be very cautious and give plenty of time for an event to occur.



                      I would say that a few minutes or even hours is not enough today.
                      Is one day enough ? I would tend to think so but I'm not even certain.







                      share|improve this answer












                      share|improve this answer



                      share|improve this answer










                      answered 11 hours ago









                      FFFFFF

                      621212




                      621212













                      • If I'm experimenting with building something that can hit milestones during smaller ranges. Kind of curious how close those milestones can be.

                        – Rob
                        9 hours ago






                      • 2





                        Understood but let's all remember Fomo3d medium.com/coinmonks/… on Ethereum before requiring milestones too fast.

                        – FFF
                        9 hours ago



















                      • If I'm experimenting with building something that can hit milestones during smaller ranges. Kind of curious how close those milestones can be.

                        – Rob
                        9 hours ago






                      • 2





                        Understood but let's all remember Fomo3d medium.com/coinmonks/… on Ethereum before requiring milestones too fast.

                        – FFF
                        9 hours ago

















                      If I'm experimenting with building something that can hit milestones during smaller ranges. Kind of curious how close those milestones can be.

                      – Rob
                      9 hours ago





                      If I'm experimenting with building something that can hit milestones during smaller ranges. Kind of curious how close those milestones can be.

                      – Rob
                      9 hours ago




                      2




                      2





                      Understood but let's all remember Fomo3d medium.com/coinmonks/… on Ethereum before requiring milestones too fast.

                      – FFF
                      9 hours ago





                      Understood but let's all remember Fomo3d medium.com/coinmonks/… on Ethereum before requiring milestones too fast.

                      – FFF
                      9 hours ago











                      2














                      The baker chooses the value of NOW. I am aware of these two constraints:



                      The protocol enforces that the timestamp is at least the minimal timestamp at which the baker was supposed to bake (some delay after the previous block's timestamp): baking.ml.



                      The shell will also ignore a block whose timestamp is too far in the future (more than 15s) relative to the system clock: distributed_db.ml.






                      share|improve this answer




























                        2














                        The baker chooses the value of NOW. I am aware of these two constraints:



                        The protocol enforces that the timestamp is at least the minimal timestamp at which the baker was supposed to bake (some delay after the previous block's timestamp): baking.ml.



                        The shell will also ignore a block whose timestamp is too far in the future (more than 15s) relative to the system clock: distributed_db.ml.






                        share|improve this answer


























                          2












                          2








                          2







                          The baker chooses the value of NOW. I am aware of these two constraints:



                          The protocol enforces that the timestamp is at least the minimal timestamp at which the baker was supposed to bake (some delay after the previous block's timestamp): baking.ml.



                          The shell will also ignore a block whose timestamp is too far in the future (more than 15s) relative to the system clock: distributed_db.ml.






                          share|improve this answer













                          The baker chooses the value of NOW. I am aware of these two constraints:



                          The protocol enforces that the timestamp is at least the minimal timestamp at which the baker was supposed to bake (some delay after the previous block's timestamp): baking.ml.



                          The shell will also ignore a block whose timestamp is too far in the future (more than 15s) relative to the system clock: distributed_db.ml.







                          share|improve this answer












                          share|improve this answer



                          share|improve this answer










                          answered 7 hours ago









                          TomTom

                          87327




                          87327






























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