pub struct MessageHeader {
    pub num_required_signatures: u8,
    pub num_readonly_signed_accounts: u8,
    pub num_readonly_unsigned_accounts: u8,
}
Expand description

Describes the organization of a Message’s account keys.

Every Instruction specifies which accounts it may reference, or otherwise requires specific permissions of. Those specifications are: whether the account is read-only, or read-write; and whether the account must have signed the transaction containing the instruction.

Whereas individual Instructions contain a list of all accounts they may access, along with their required permissions, a Message contains a single shared flat list of all accounts required by all instructions in a transaction. When building a Message, this flat list is created and Instructions are converted to CompiledInstructions. Those CompiledInstructions then reference by index the accounts they require in the single shared account list.

The shared account list is ordered by the permissions required of the accounts:

  • accounts that are writable and signers
  • accounts that are read-only and signers
  • accounts that are writable and not signers
  • accounts that are read-only and not signers

Given this ordering, the fields of MessageHeader describe which accounts in a transaction require which permissions.

When multiple transactions access the same read-only accounts, the runtime may process them in parallel, in a single PoH entry. Transactions that access the same read-write accounts are processed sequentially.

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§num_required_signatures: u8

The number of signatures required for this message to be considered valid. The signers of those signatures must match the first num_required_signatures of Message::account_keys.

§num_readonly_signed_accounts: u8

The last num_readonly_signed_accounts of the signed keys are read-only accounts.

§num_readonly_unsigned_accounts: u8

The last num_readonly_unsigned_accounts of the unsigned keys are read-only accounts.

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impl AbiExample for MessageHeader

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impl Clone for MessageHeader

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fn clone(&self) -> MessageHeader

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for MessageHeader

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl Default for MessageHeader

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fn default() -> MessageHeader

Returns the “default value” for a type. Read more
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impl<'de> Deserialize<'de> for MessageHeader

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fn deserialize<__D>( __deserializer: __D ) -> Result<MessageHeader, <__D as Deserializer<'de>>::Error>where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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impl PartialEq<MessageHeader> for MessageHeader

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fn eq(&self, other: &MessageHeader) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Serialize for MessageHeader

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fn serialize<__S>( &self, __serializer: __S ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>where __S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl Copy for MessageHeader

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impl Eq for MessageHeader

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impl StructuralEq for MessageHeader

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impl StructuralPartialEq for MessageHeader

Auto Trait Implementations§

Blanket Implementations§

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impl<T> AbiEnumVisitor for Twhere T: Serialize + AbiExample + ?Sized,

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default fn visit_for_abi( &self, digester: &mut AbiDigester ) -> Result<AbiDigester, DigestError>

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impl<T> AbiEnumVisitor for Twhere T: Serialize + ?Sized,

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default fn visit_for_abi( &self, _digester: &mut AbiDigester ) -> Result<AbiDigester, DigestError>

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impl<T> AbiExample for T

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default fn example() -> T

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Pointable for T

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const ALIGN: usize = mem::align_of::<T>()

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same<T> for T

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type Output = T

Should always be Self
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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for Twhere V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> DeserializeOwned for Twhere T: for<'de> Deserialize<'de>,