1. 概述
在本篇 Reddit 应用案例研究 中，我们将开始记录每篇帖子的提交尝试历史，并对状态进行更详细、更易读的描述，提升系统的可观测性。
这个改动看似小，但在实际运维中非常实用——当某个帖子反复提交失败时，你不再需要翻日志猜原因，所有信息一目了然。✅
2. 改进 Post 实体
首先，我们替换掉原来用 String 表示的简单状态字段，引入一个专门的实体来记录每次提交的详细信息。
在 Post 实体中添加一个一对多的关联：
public class Post {
...
@OneToMany(fetch = FetchType.EAGER, mappedBy = "post")
private List<SubmissionResponse> submissionsResponse;
}
接下来是核心的 SubmissionResponse 实体，用于记录每次提交的完整上下文：
@Entity
public class SubmissionResponse implements IEntity {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private int attemptNumber;
private String content;
private Date submissionDate;
private Date scoreCheckDate;
@JsonIgnore
@ManyToOne
@JoinColumn(name = "post_id", nullable = false)
private Post post;
public SubmissionResponse(int attemptNumber, String content, Post post) {
super();
this.attemptNumber = attemptNumber;
this.content = content;
this.submissionDate = new Date();
this.post = post;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("Attempt No ").append(attemptNumber).append(" : ").append(content);
return builder.toString();
}
}
每个提交尝试对应一条 SubmissionResponse 记录，包含以下关键字段：
- ✅
attemptNumber：第几次尝试 - ✅
content：本次尝试的详细结果（成功/失败原因） - ✅
submissionDate：提交时间 - ✅
scoreCheckDate：本次尝试中检查 Reddit 帖子分数的时间
配套的 JPA 仓库接口也很简单：
public interface SubmissionResponseRepository extends JpaRepository<SubmissionResponse, Long> {
SubmissionResponse findOneByPostAndAttemptNumber(Post post, int attemptNumber);
}
3. 调度服务逻辑改造
现在我们要在服务层记录这些历史信息，第一步是让成功/失败的原因更清晰可读。
构建可读的成败原因
我们定义了两个模板字符串，用于生成标准化的提示信息：
private final static String SCORE_TEMPLATE = "score %d %s minimum score %d";
private final static String TOTAL_VOTES_TEMPLATE = "total votes %d %s minimum total votes %d";
然后是两个核心方法，用于生成失败和成功的原因：
protected String getFailReason(Post post, PostScores postScores) {
StringBuilder builder = new StringBuilder();
builder.append("Failed because ");
builder.append(String.format(
SCORE_TEMPLATE, postScores.getScore(), "<", post.getMinScoreRequired()));
if (post.getMinTotalVotes() > 0) {
builder.append(" and ");
builder.append(String.format(TOTAL_VOTES_TEMPLATE,
postScores.getTotalVotes(), "<", post.getMinTotalVotes()));
}
if (post.isKeepIfHasComments()) {
builder.append(" and has no comments");
}
return builder.toString();
}
protected String getSuccessReason(Post post, PostScores postScores) {
StringBuilder builder = new StringBuilder();
if (postScores.getScore() >= post.getMinScoreRequired()) {
builder.append("Succeed because ");
builder.append(String.format(SCORE_TEMPLATE,
postScores.getScore(), ">=", post.getMinScoreRequired()));
return builder.toString();
}
if (
(post.getMinTotalVotes() > 0) &&
(postScores.getTotalVotes() >= post.getMinTotalVotes())
) {
builder.append("Succeed because ");
builder.append(String.format(TOTAL_VOTES_TEMPLATE,
postScores.getTotalVotes(), ">=", post.getMinTotalVotes()));
return builder.toString();
}
return "Succeed because has comments";
}
更新核心调度逻辑
接下来改造原有的调度逻辑，加入历史记录：
private void submitPost(...) {
...
if (errorNode == null) {
post.setSubmissionsResponse(addAttemptResponse(post, "Submitted to Reddit"));
...
} else {
post.setSubmissionsResponse(addAttemptResponse(post, errorNode.toString()));
...
}
}
private void checkAndReSubmit(Post post) {
if (didIntervalPass(...)) {
PostScores postScores = getPostScores(post);
if (didPostGoalFail(post, postScores)) {
...
resetPost(post, getFailReason(post, postScores));
} else {
...
updateLastAttemptResponse(
post, "Post reached target score successfully " +
getSuccessReason(post, postScores));
}
}
}
private void checkAndDeleteInternal(Post post) {
if (didIntervalPass(...)) {
PostScores postScores = getPostScores(post);
if (didPostGoalFail(post, postScores)) {
updateLastAttemptResponse(post,
"Deleted from reddit, consumed all attempts without reaching score " +
getFailReason(post, postScores));
...
} else {
updateLastAttemptResponse(post,
"Post reached target score successfully " +
getSuccessReason(post, postScores));
...
}
}
}
private void resetPost(Post post, String failReason) {
...
updateLastAttemptResponse(post, "Deleted from Reddit, to be resubmitted " + failReason);
...
}
⚠️ 注意两个底层方法的作用：
addAttemptResponse()：每次提交时创建新的SubmissionResponse记录updateLastAttemptResponse()：在检查分数时更新最后一次尝试的结果
这样就能完整记录“提交 → 检查 → 失败/成功”的整个生命周期。
4. 调度帖子 DTO 改造
为了让前端能拿到这些历史数据，我们需要更新 DTO。
ScheduledPostDto
public class ScheduledPostDto {
...
private String status;
private List<SubmissionResponseDto> detailedStatus;
}
SubmissionResponseDto
public class SubmissionResponseDto {
private int attemptNumber;
private String content;
private String localSubmissionDate;
private String localScoreCheckDate;
}
转换逻辑
在 ScheduledPostRestController 中更新转换方法：
private ScheduledPostDto convertToDto(Post post) {
...
List<SubmissionResponse> response = post.getSubmissionsResponse();
if ((response != null) && (response.size() > 0)) {
postDto.setStatus(response.get(response.size() - 1).toString().substring(0, 30));
List<SubmissionResponseDto> responsedto =
post.getSubmissionsResponse().stream().
map(res -> generateResponseDto(res)).collect(Collectors.toList());
postDto.setDetailedStatus(responsedto);
} else {
postDto.setStatus("Not sent yet");
postDto.setDetailedStatus(Collections.emptyList());
}
return postDto;
}
private SubmissionResponseDto generateResponseDto(SubmissionResponse responseEntity) {
SubmissionResponseDto dto = modelMapper.map(responseEntity, SubmissionResponseDto.class);
String timezone = userService.getCurrentUser().getPreference().getTimezone();
dto.setLocalSubmissionDate(responseEntity.getSubmissionDate(), timezone);
if (responseEntity.getScoreCheckDate() != null) {
dto.setLocalScoreCheckDate(responseEntity.getScoreCheckDate(), timezone);
}
return dto;
}
这里做了两件事：
- ✅
status字段显示最近一次尝试的摘要（截取前30字符） - ✅
detailedStatus返回完整的尝试历史，且时间已转换为用户本地时区
5. 前端展示
前端 scheduledPosts.jsp 也需相应调整，支持查看详细历史。
<div class="modal">
<h4 class="modal-title">Detailed Status</h4>
<table id="res"></table>
</div>
<script >
var loadedData = [];
var detailedResTable = $('#res').DataTable( {
"searching":false,
"paging": false,
columns: [
{ title: "Attempt Number", data: "attemptNumber" },
{ title: "Detailed Status", data: "content" },
{ title: "Attempt Submitted At", data: "localSubmissionDate" },
{ title: "Attempt Score Checked At", data: "localScoreCheckDate" }
]
} );
$(document).ready(function() {
$('#myposts').dataTable( {
...
"columnDefs": [
{ "targets": 2, "data": "status",
"render": function ( data, type, full, meta ) {
return data +
' <a href="#" onclick="showDetailedStatus('+meta.row+' )">More Details</a>';
}
},
....
],
...
});
});
function showDetailedStatus(row){
detailedResTable.clear().rows.add(loadedData[row].detailedStatus).draw();
$('.modal').modal();
}
</script>
效果很简单粗暴：
- 表格每行的
status后面加个 “More Details” 链接 - 点击后弹出 modal，用 DataTable 展示完整的提交历史
- 包含尝试次数、内容、提交时间、评分检查时间
6. 单元测试
最后别忘了给新加的逻辑补上单元测试，避免踩坑。
测试 getSuccessReason
@Test
public void whenHasEnoughScore_thenSucceed() {
Post post = new Post();
post.setMinScoreRequired(5);
PostScores postScores = new PostScores(6, 10, 1);
assertTrue(getSuccessReason(post, postScores).contains("Succeed because score"));
}
@Test
public void whenHasEnoughTotalVotes_thenSucceed() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setMinTotalVotes(8);
PostScores postScores = new PostScores(2, 10, 1);
assertTrue(getSuccessReason(post, postScores).contains("Succeed because total votes"));
}
@Test
public void givenKeepPostIfHasComments_whenHasComments_thenSucceed() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setKeepIfHasComments(true);
final PostScores postScores = new PostScores(2, 10, 1);
assertTrue(getSuccessReason(post, postScores).contains("Succeed because has comments"));
}
测试 getFailReason
@Test
public void whenNotEnoughScore_thenFail() {
Post post = new Post();
post.setMinScoreRequired(5);
PostScores postScores = new PostScores(2, 10, 1);
assertTrue(getFailReason(post, postScores).contains("Failed because score"));
}
@Test
public void whenNotEnoughTotalVotes_thenFail() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setMinTotalVotes(15);
PostScores postScores = new PostScores(2, 10, 1);
String reason = getFailReason(post, postScores);
assertTrue(reason.contains("Failed because score"));
assertTrue(reason.contains("and total votes"));
}
@Test
public void givenKeepPostIfHasComments_whenNotHasComments_thenFail() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setKeepIfHasComments(true);
final PostScores postScores = new PostScores(2, 10, 0);
String reason = getFailReason(post, postScores);
assertTrue(reason.contains("Failed because score"));
assertTrue(reason.contains("and has no comments"));
}
这些测试覆盖了主要分支，确保提示信息生成正确。
7. 总结
通过本次改造，我们为 Reddit 帖子的生命周期增加了完整的提交历史追踪能力。
现在你可以清晰地看到：
- ✅ 每次提交的时间和结果
- ✅ 每次检查分数的时间
- ✅ 失败或成功的确切原因（基于分数、投票数、评论数）
这个改动虽然不大，但极大提升了系统的可观测性和调试效率。当你收到告警时，不再需要查日志、问同事，直接看前端就能定位问题。这才是真正面向运维的设计。✅