Struct ContentHasher 

pub struct ContentHasher;

Content hasher for deduplication.

Normalizes content and produces SHA256 hashes for exact match detection.

Normalization

Before hashing, content is normalized:

• Trimmed of leading/trailing whitespace
• Converted to lowercase
• Multiple whitespace characters collapsed to single spaces

Example

use subcog::services::deduplication::ContentHasher;

let hash = ContentHasher::hash("Use PostgreSQL for primary storage");
assert_eq!(hash.len(), 64); // SHA256 produces 64 hex chars

// Normalized content produces the same hash
let hash2 = ContentHasher::hash("  Use  postgresql  for  primary  storage  ");
assert_eq!(hash, hash2);

Implementations

impl ContentHasher

pub fn hash(content: &str) -> String

Computes the SHA256 hash of normalized content.

Arguments

• content - The content to hash

Returns

The lowercase hex-encoded SHA256 hash (64 characters).

Example

use subcog::services::deduplication::ContentHasher;

let hash = ContentHasher::hash("Hello, world!");
assert_eq!(hash.len(), 64);

pub fn hash_to_tag(hash: &str) -> String

Converts a hash to a tag format.

The tag format is hash:sha256:<16-char-prefix>.

Arguments

• hash - The full SHA256 hash

Returns

The hash tag string.

Panics

Does not panic. If the hash is shorter than 16 chars, uses the full hash.

Example

use subcog::services::deduplication::ContentHasher;

let hash = ContentHasher::hash("test content");
let tag = ContentHasher::hash_to_tag(&hash);
assert!(tag.starts_with("hash:sha256:"));
assert_eq!(tag.len(), "hash:sha256:".len() + 16);

pub fn content_to_tag(content: &str) -> String

Computes a hash and returns it in tag format.

Convenience method that combines hash() and hash_to_tag().

Arguments

• content - The content to hash

Returns

The hash tag string.

Example

use subcog::services::deduplication::ContentHasher;

let tag = ContentHasher::content_to_tag("Use PostgreSQL");
assert!(tag.starts_with("hash:sha256:"));

pub fn normalize(content: &str) -> String

Normalizes content for consistent hashing.

Normalization steps:

1. Trim leading/trailing whitespace
2. Convert to lowercase
3. Collapse multiple whitespace to single space

Arguments

• content - The content to normalize

Returns

The normalized content string.

Example

use subcog::services::deduplication::ContentHasher;

let normalized = ContentHasher::normalize("  Hello   WORLD  ");
assert_eq!(normalized, "hello world");