Struct MessageHeader

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

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.

Fields

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.

Trait Implementations

impl Clone for MessageHeader

fn clone(&self) -> MessageHeader

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MessageHeader

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

Formats the value using the given formatter.

impl Default for MessageHeader

fn default() -> MessageHeader

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for MessageHeader

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for MessageHeader

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

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for MessageHeader

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for MessageHeader

impl Eq for MessageHeader

impl StructuralPartialEq for MessageHeader