Cache User Profiles in Memory: Code Review Practice

The profile endpoint is our most-read route, and every request goes to the database. This adds a map in front of the repository so repeat reads of the same profile skip the query. Locally, p95 for GET /users/{id}/profile dropped from 38 ms to 2 ms. updateProfile now reads straight from the repository so it always edits the latest data.

Msrc/main/java/com/acme/profile/ProfileService.java1 of 2

Files Changed

src/main/java/com/acme/profile/

src/test/java/com/acme/profile/

src/main/java/com/acme/profile/ProfileService.java

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@@ -1,26 +1,37 @@

package com.acme.profile;

import java.util.HashMap;

import java.util.Map;

import org.springframework.stereotype.Service;

import org.springframework.transaction.annotation.Transactional;

@Service

public class ProfileService {

private final ProfileRepository repository;

private final Map<Long, Profile> cache = new HashMap<>();

public ProfileService(ProfileRepository repository) {

this.repository = repository;

}

public Profile getProfile(long userId) {

return repository.findById(userId)

Profile cached = cache.get(userId);

if (cached != null) {

return cached;

}

Profile profile = repository.findById(userId)

.orElseThrow(() -> new ProfileNotFoundException(userId));

cache.put(userId, profile);

return profile;

}

@Transactional

public Profile updateProfile(long userId, ProfileUpdate update) {

Profile profile = getProfile(userId);

Profile profile = repository.findById(userId)

.orElseThrow(() -> new ProfileNotFoundException(userId));

profile.setDisplayName(update.displayName());

profile.setBio(update.bio());

return repository.save(profile);

}

Cache User Profiles in Memory

src/main/java/com/acme/profile/ProfileService.java

src/test/java/com/acme/profile/ProfileServiceTest.java