Genesis Contract Documentation.

docs-sphinx/reference/smart-contract/genesis-contract.md

@@ -26,3 +26,115 @@ message SmartContractRegistration {
     bool is_user_contract = 8;
 }
 ```
+Smart Contract code is store in the `code` field.
+
+However, each `SmartContractRegistration` entity is not a one-to-one correspondence with the contract, and its storage structure is:
+
+```C#
+public MappedState<Hash, SmartContractRegistration> SmartContractRegistrations { get; set; }
+```
+
+`SmartContractRegistration` entity can be fetched by the hash value of the contract code. In fact, it is only written once when deploying the contract.
+
+The data structure that corresponds one-to-one with contracts is called `ContractInfo`.
+Structure `ContractInfo` is defined in `acs0.proto`.
+
+```C#
+message ContractInfo
+{
+    // The serial number of the contract.
+    int64 serial_number = 1;
+    // The author of the contract, this is the person who deployed the contract.
+    aelf.Address author = 2;
+    // The category of contract code(0: C#).
+    sint32 category = 3;
+    // The hash of the contract code.
+    aelf.Hash code_hash = 4;
+    // Whether it is a system contract.
+    bool is_system_contract = 5;
+    // The version of the current contract.
+    int32 version = 6;
+    string contract_version = 7;
+    // Indicates if the contract is the user contract.
+    bool is_user_contract = 8;
+}
+```
+
+We use the MappedState to store related instances.
+
+```C#
+public MappedState<Address, ContractInfo> ContractInfos { get; set; }
+```
+
+From the `code_hash` field of `ContractInfo`, it is not difficult to guess:
+
+1. When trying to retrieve the contract code, the `code_hash` of ContractInfo is first read, and then the contract code itself is read from `State.SmartContractRegistrations` mapped state.
+2. Upgrading a contract on aelf is actually replacing the `code_hash` of `ContractInfo`.
+
+# Calculation of contract address
+
+The contract address is actually calculated through a field that increases with the number of contract deployments.
+
+```C#
+public Int64State ContractSerialNumber { get; set; }
+```
+
+Its calculation process is located in the `DeploySmartContract` method:
+
+```C#
+var contractAddress = AddressHelper.BuildContractAddress(Context.ChainId, serialNumber);
+```
+
+- The contract address of each chain of aelf is different.
+- The contract address is not related to the contract code, but only to the order in which it is deployed on this chain.
+    - Therefore, when testing newly written contracts in `aelf-boilerplate` or `aelf-developer-tools`, the new contract always has a fixed address.
+
+After the 1.6.0 version, Salt is added to the imported parameter of the deployment/upgrade contract. The contract address is calculated by using the Deployer address of the deployment account and the hash value Salt.
+
+```C#
+var contractAddress = AddressHelper.ComputeContractAddress(deployer, salt);
+```
+
+- Deploying contracts with the same account and using the same Salt can make the contract address of each chain of aelf the same.
+
+# Contract deployment and update process
+
+## Deploy contract with audit
+
+The current pipeline starts with Propose, which generates a parliamentary proposal.
+When more than 2/3 of the BPs agree to deploy/update, a new proposal is released to request code inspection. 
+Finally, after the code inspection is passed, the real contract deployment/upgrade will be achieved through the proposal of releasing code inspection.
+
+## Deploy contract without audit
+
+Developers send deployment/update user contract transactions, generate a parliamentary CodeCheck proposal, and when more than 2/3 of the BPs conduct code checks and pass, achieve real contract deployment/upgrade through the proposal of automatically releasing code checks.
+
+## Contract deployment and upgrade new version number
+
+When upgrading a contract, check the contract version information
+- If the contract version is less than or equal to the original contract version, the upgrade contract transaction fails
+  The old version of the contract only has a version number after being upgraded.
+- If the version number is increasing , the upgrade contract transaction is successful.
+
+In the updateSmartContract method, increase the version number judgment:
+
+```C#
+var contractInfo = Context.UpdateSmartContract(contractAddress, reg, null, info.ContractVersion);
+Assert(contractInfo.IsSubsequentVersion,
+    $"The version to be deployed is lower than the effective version({info.ContractVersion}), please correct the version number.");
+```
+
+# Contract error message
+
+
+| Method | Error message | Note |
+| --- | --- | --- |
+| DeployUserSmartContract | No permission. | Trying to deploy smart contract to an aelf private sidechain, and the transaction sender is not in allowlist. |
+|  | contract code has already been deployed before. | Contract code deployed  |
+|  | Already proposed. | Duplicate deployment request |
+| UpdateUserSmartContract | Contract not found. | Contract does not exist |
+|  | No permission. | The updated contract author is not myself |
+|  | Code is not changed. | The contract code has not changed |
+|  | contract code has already been deployed before. | Contract code deployed |
+|  | The version to be deployed is lower than the effective version({currentVersion}), please correct the version number. | Updated contract version number is too low  |
+|  | Already proposed. | Duplicate update request |