The specific function within a program that processes a particular instruction variant. In native Solana programs, the entrypoint dispatches to different handler functions based on instruction data. In Anchor, each pub fn in the #[program] module is an instruction handler that is automatically routed to via the 8-byte discriminator prefix in the instruction data.
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The specific function within a program that processes a particular instruction variant. In native Solana programs, the entrypoint dispatches to different handler functions based on instruction data. In Anchor, each pub fn in the #[program] module is an instruction handler that is automatically routed to via the 8-byte discriminator prefix in the instruction data.
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Accounts, instructions, PDAs, transactions, and execution flow.
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Instruction Handler (instruction-handler) Category: Programming Model Definition: The specific function within a program that processes a particular instruction variant. In native Solana programs, the entrypoint dispatches to different handler functions based on instruction data. In Anchor, each pub fn in the #[program] module is an instruction handler that is automatically routed to via the 8-byte discriminator prefix in the instruction data. Related: Instruction, Entrypoint, Discriminator
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A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.
The function that the Solana runtime calls when a program is invoked. Native programs use the `entrypoint!()` macro which exposes a function with signature `fn(program_id, accounts, instruction_data) -> ProgramResult`. Anchor generates the entrypoint automatically and routes to the correct handler based on the instruction discriminator.
An 8-byte identifier prepended to account data and instruction data to distinguish types. Anchor computes it as the first 8 bytes of `sha256('account:<AccountName>')` for accounts and `sha256('global:<function_name>')` for instructions. Discriminators prevent type cosplay attacks by ensuring data is deserialized as the correct type.
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A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.
An instruction generated during cross-program invocation (CPI) that appears in a transaction's metadata as a nested instruction under its parent. Inner instructions are not declared in the original transaction message but are produced at runtime when a program calls another program via invoke or invoke_signed. They are visible in explorers and via the getTransaction RPC method's innerInstructions field.
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A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.
The function that the Solana runtime calls when a program is invoked. Native programs use the `entrypoint!()` macro which exposes a function with signature `fn(program_id, accounts, instruction_data) -> ProgramResult`. Anchor generates the entrypoint automatically and routes to the correct handler based on the instruction discriminator.
An 8-byte identifier prepended to account data and instruction data to distinguish types. Anchor computes it as the first 8 bytes of `sha256('account:<AccountName>')` for accounts and `sha256('global:<function_name>')` for instructions. Discriminators prevent type cosplay attacks by ensuring data is deserialized as the correct type.
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The fundamental data storage unit on Solana. Every piece of state is stored in an account identified by a 32-byte public key. Accounts hold a lamport balance, an owner program, a data byte array (up to 10MB), and an executable flag. Only the owning program can modify an account's data, but anyone can credit lamports to it.
Executable code deployed on-chain, equivalent to a smart contract on other blockchains. Programs are stateless—they store no data themselves but read/write data in separate accounts they own. Programs are compiled to SBF bytecode and loaded via the BPF Loader. Every program has a unique Program ID (its account's public key).
A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.
An atomic unit of execution containing one or more instructions, a recent blockhash, and one or more signatures. All instructions in a transaction execute sequentially and atomically—if any instruction fails, the entire transaction reverts. Transactions have a 1,232-byte size limit (matching IPv6 MTU) and a default 200,000 CU budget.