fees.go

Overview

The [fees.go](/projects/291/69231) file is part of the `cosmos` package and provides functionality for retrieving minimum gas price information from a Cosmos SDK-based blockchain network. It interacts with the blockchain's REST API (LCD - Light Client Daemon) to fetch two types of gas prices:

• Global Minimum Gas Prices: Obtained from the feemarket module, representing the globally suggested minimum gas prices for transactions.

• Local Minimum Gas Prices: Obtained from the node's local configuration, representing the node-specific configured minimum gas prices.

This information is crucial for clients constructing transactions to ensure their fees meet the minimum network requirements to be accepted and processed.

Detailed Description of Functions

1. GetGlobalMinimumGasPrices

func (c *HTTPClient) GetGlobalMinimumGasPrices() (map[string]sdkmath.LegacyDec, error)

Purpose

Fetches the global minimum gas prices from the feemarket module of the blockchain by querying the LCD endpoint `/feemarket/v1/gas_price/{denom}`.

Parameters

• No explicit parameters; it uses the denom property of the HTTPClient receiver to specify the token denomination.

Returns

• map[string]sdkmath.LegacyDec: A map where keys are coin denominations (e.g., "uatom") and values are their corresponding gas prices represented as LegacyDec decimal values.

• error: Non-nil if an error occurs during the HTTP request, response parsing, or decimal conversion.

Description

• Constructs the URL endpoint using the denomination (c.denom).

• Sends a GET request to the fee market gas price endpoint.

• Parses the JSON response into an internal struct.

• Converts the amount string to a LegacyDec decimal type.

• Returns a map associating denominations with their gas prices.

Usage Example

client := &cosmos.HTTPClient{denom: "uatom", /* ... other fields ... */}
gasPrices, err := client.GetGlobalMinimumGasPrices()
if err != nil {
    log.Fatalf("Error fetching global gas prices: %v", err)
}
fmt.Println("Global Minimum Gas Prices:", gasPrices)

2. GetLocalMinimumGasPrices

func (c *HTTPClient) GetLocalMinimumGasPrices() (map[string]sdkmath.LegacyDec, error)

Purpose

Retrieves the local node's configured minimum gas prices from the node's base configuration endpoint `/cosmos/base/node/v1beta1/config`.

Parameters

• None explicitly; uses the HTTPClient receiver for making HTTP requests.

Returns

• map[string]sdkmath.LegacyDec: Map of coin denominations to their respective minimum gas prices.

• error: Non-nil if there is a failure in HTTP request, parsing the response, or decoding coin strings.

Description

• Sends a GET request to the node configuration endpoint.

• Extracts the minimum_gas_price string from the response.

• Parses the string (which can represent multiple coins, e.g., "0.025uatom,0.001stake") into a slice of DecCoin.

• Converts the parsed coins into a map for easy access by denomination.

Usage Example

client := &cosmos.HTTPClient{ /* ... */ }
localGasPrices, err := client.GetLocalMinimumGasPrices()
if err != nil {
    log.Fatalf("Error fetching local gas prices: %v", err)
}
fmt.Println("Local Minimum Gas Prices:", localGasPrices)

Important Implementation Details

• Error Handling: Both functions use structured error handling to wrap and return errors encountered during HTTP requests, JSON unmarshalling, or parsing operations. They also handle API-level errors by checking the error response (ErrorResponse) returned by the LCD.

• Use of sdkmath.LegacyDec: Gas prices are represented using LegacyDec from the Cosmos SDK's math package, a fixed-point decimal type designed for precision in financial calculations.

• HTTP Client (HTTPClient): The methods are bound to HTTPClient, which internally uses c.LCD (likely a REST client) to interact with the blockchain's LCD endpoints.

• Parsing Coins: The local gas price string is parsed using sdk.ParseDecCoins, which supports multiple coin denominations in a single string.

Interaction with Other System Components

• HTTPClient and LCD: The HTTPClient struct acts as a wrapper around a REST client (c.LCD) that communicates with the blockchain's LCD endpoints. This file depends on this client to fetch real-time blockchain configuration data.

• Cosmos SDK Types: The file leverages Cosmos SDK types such as sdkmath.LegacyDec and sdk.DecCoin for precise and standardized representation of coin amounts and denominations.

• ErrorResponse: Uses a custom ErrorResponse struct (definition not included here) to capture and handle error messages returned by the LCD.

• Modules Queried:

  • feemarket: Provides global network fee parameters.

  • base node config: Provides node-specific configuration, including local fee settings.

This file is likely used by higher-level modules responsible for transaction creation, fee estimation, and validation to ensure transactions include appropriate fees.

Mermaid Diagram: Flowchart of Main Functions and Their Relationships

flowchart TD
    A[HTTPClient] --> B[GetGlobalMinimumGasPrices]
    A --> C[GetLocalMinimumGasPrices]

    B --> D{HTTP GET /feemarket/v1/gas_price/{denom}}
    D --> E[Parse JSON response]
    E --> F[Convert amount to LegacyDec]
    F --> G[Return map[denom]LegacyDec]

    C --> H{HTTP GET /cosmos/base/node/v1beta1/config}
    H --> I[Parse JSON response]
    I --> J[Parse minimum_gas_price string to DecCoins]
    J --> K[Build map[denom]LegacyDec]
    K --> L[Return gas prices map]

    subgraph ErrorHandling
        D -- On failure --> M[Return error]
        H -- On failure --> M
        E -- On failure --> M
        I -- On failure --> M
        F -- On failure --> M
        J -- On failure --> M
    end

Summary

The [fees.go](/projects/291/69231) file provides essential utilities for querying minimum gas price information from a Cosmos SDK blockchain's REST API. It exposes two primary methods for retrieving global and local gas price configurations, handling all necessary API interactions, JSON unmarshalling, and error handling internally. This functionality supports fee management in transaction processing workflows, ensuring clients can dynamically adjust to network fee requirements.

If you require further details about the `HTTPClient` struct or `ErrorResponse` type, please refer to their respective source files in the `cosmos` package.