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Some updates to gas and delegatecall.

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chriseth 2022-04-07 20:29:07 +02:00 committed by Kamil Śliwak
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docs/introduction-to-smart-contracts.rst
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@ -396,26 +396,33 @@ returns that code when executed.
Gas Gas
=== ===
Upon creation, each transaction is charged with a certain amount of **gas**. Upon creation, each transaction is charged with a certain amount of **gas**
Imposing a cost on transactions serves to secure the network: that has to be paid for by the originator of the transaction (``tx.origin``).
it deincentivizes bad actors from spamming, and pays validators (i.e. miners and stakers) While the EVM executes the
for the work that is required to validate new blocks. While the EVM executes the
transaction, the gas is gradually depleted according to specific rules. transaction, the gas is gradually depleted according to specific rules.
The **gas price** is a value set by the originator of the transaction, i.e. `tx.origin`, who
has to pay ``gas_price * gas`` up front from the sending account.
If some gas is left after execution, it is refunded to the transaction originator.
If the gas is used up at any point (i.e. it would be negative), If the gas is used up at any point (i.e. it would be negative),
an out-of-gas exception is triggered, which reverts all modifications an out-of-gas exception is triggered, which ends execution and reverts all modifications
made to the state in the current call frame. made to the state in the current call frame.
This mechanism incentivizes economical use of EVM execution time
and also compensates EVM executors (i.e. miners / stakers) for their work.
Since each block has a maximum amount of gas, it also limits the amount
of work needed to validate a block.
The **gas price** is a value set by the originator of the transaction, who
has to pay ``gas_price * gas`` up front to the EVM executor.
If some gas is left after execution, it is refunded to the transaction originator.
In case of an exception that reverts changes, already used up gas is not refunded.
Since EVM executors can choose to include a transaction or not,
transaction senders cannot abuse the system by setting a low gas price.
.. index:: ! storage, ! memory, ! stack .. index:: ! storage, ! memory, ! stack
Storage, Memory and the Stack Storage, Memory and the Stack
============================= =============================
The Ethereum Virtual Machine has three areas where it can store data- The Ethereum Virtual Machine has three areas where it can store data:
storage, memory and the stack. storage, memory and the stack.
Each account has a data area called **storage**, which is persistent between function calls Each account has a data area called **storage**, which is persistent between function calls
@ -504,10 +511,8 @@ Delegatecall / Callcode and Libraries
There exists a special variant of a message call, named **delegatecall** There exists a special variant of a message call, named **delegatecall**
which is identical to a message call apart from the fact that which is identical to a message call apart from the fact that
the code at the target address is executed in the context of the calling the code at the target address is executed in the context (i.e. at the address) of the calling
contract. In practice this means ``msg.sender`` and ``msg.value`` retain contract and ``msg.sender`` and ``msg.value`` do not change their values.
the values that were passed to the delegator, while executing code that
lives in the delegated contract.
This means that a contract can dynamically load code from a different This means that a contract can dynamically load code from a different
address at runtime. Storage, current address and balance still address at runtime. Storage, current address and balance still