package tezos-protocol-014-PtKathma
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doc/tezos-protocol-014-PtKathma.raw/Tezos_raw_protocol_014_PtKathma/Alpha_context/Gas/index.html
Module Alpha_context.GasSource
This module implements the gas subsystem of the context.
Gas reflects the computational cost of each operation to limit the cost of operations and, by extension, the cost of blocks.
There are two gas quotas: one for operation and one for block. For this reason, we maintain two gas levels -- one for operations and another one for blocks -- that correspond to the remaining amounts of gas, initialized with the quota limits and decreased each time gas is consumed.
module Arith :
Fixed_point_repr.Safe
with type 'a t = private Saturation_repr.may_saturate Saturation_repr.tFor maintenance operations or for testing, gas can be Unaccounted. Otherwise, the computation is Limited by the remaining gas in the context.
set_limit ctxt limit returns a context with a given limit level of gas allocated for an operation.
remaining_operation_gas ctxt returns the current gas level in the context ctxt for the current operation. If gas is Unaccounted, an arbitrary value will be returned.
reset_block_gas ctxt returns a context where the remaining gas in the block is reset to the constant hard_gas_limit_per_block, i.e., as if no operations have been included in the block.
/!\ Do not call this function unless you want to validate operations on their own (like in the mempool).
level ctxt is the current gas level in ctxt for the current operation.
update_remaining_operation_gas ctxt remaining sets the current gas level for operations to remaining.
consumed since until is the operation gas level difference between context since and context until. This function returns Arith.zero if any of the two contexts allows for an unlimited gas consumption. This function also returns Arith.zero if since has less gas than until.
block_level ctxt returns the block gas level in context ctxt.
Costs are computed using a saturating arithmetic. See Saturation_repr.
val consume :
context ->
cost ->
context Tezos_protocol_environment_014_PtKathma.Error_monad.tzresultconsume ctxt cost subtracts cost to the current operation gas level in ctxt. This operation may fail with Operation_quota_exceeded if the operation gas level would go below zero.
val consume_from :
Arith.fp ->
cost ->
Arith.fp Tezos_protocol_environment_014_PtKathma.Error_monad.tzresultconsume_from available_gas cost subtracts cost from available_gas and returns the remaining gas.
val consume_limit_in_block :
context ->
'a Arith.t ->
context Tezos_protocol_environment_014_PtKathma.Error_monad.tzresultval check_limit_and_consume_from_block_gas :
hard_gas_limit_per_operation:Arith.integral ->
remaining_block_gas:Arith.fp ->
gas_limit:Arith.integral ->
Arith.fp Tezos_protocol_environment_014_PtKathma.Error_monad.tzresultCheck that gas_limit is a valid operation gas limit (at most hard_gas_limit_per_operation and nonnegative), then subtract it from remaining_block_gas and return the difference.
This function mimics consume_limit_in_block but bypasses the context.
Convert an amount of milligas expressed as an int to Arith.fp.
atomic_step_cost x corresponds to x milliunit of gas.
step_cost x corresponds to x units of gas.
Cost of allocating qwords of storage. alloc_cost n estimates the cost of allocating n qwords of storage.
Cost of allocating bytes in the storage. alloc_bytes_cost b estimates the cost of allocating b bytes of storage.
Cost of allocating bytes in the storage.
alloc_mbytes_cost b estimates the cost of allocating b bytes of storage and the cost of an header to describe these bytes.
Cost of reading the storage. read_bytes_cost n estimates the cost of reading n bytes of storage.
Cost of writing to storage. write_bytes_const n estimates the cost of writing n bytes to the storage.
Multiply a cost by a factor. Both arguments are saturated arithmetic values, so no negative numbers are involved.
cost_of_repr is an internal operation needed to inject costs for Storage_costs into Gas.cost.