Development Guide

This guide provides best practices, performance considerations, and practical strategies for developing applications with Telescope. It covers how to effectively use Telescope during development, avoid common pitfalls, and optimize performance. For information about configuring Telescope, see Configuration. For extending Telescope with custom watchers, see Extension and Customization.

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Development Environment Setup

Recommended Configuration for Local Development

For local development environments, configure Telescope to maximize observability while maintaining reasonable performance:

Environment Variables:

Selective Watcher Enablement: Enable only the watchers relevant to your current debugging session. For example, if debugging database issues:

Path Filtering: Use only_paths in config/telescope.php126-128 to limit recording to specific routes during feature development:

This reduces storage overhead and makes it easier to find relevant entries in the UI.

Sources: config/telescope.php1-222 src/Telescope.php125-135

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Performance Considerations

Understanding Recording Overhead

Telescope introduces three types of overhead:

Overhead Type	Phase	Impact	Mitigation
Collection	During request	Memory allocation, event listeners	Selective watcher enablement
Queueing	During request	Context manipulation, filtering	Efficient filter callbacks
Storage	Deferred/queued	Database writes, I/O operations	Defer mechanism, batch processing

Deferred Storage Mechanism

The deferred storage mechanism src/Telescope.php285-291 ensures that:

1. Recording methods return immediately (minimal request latency)
2. Storage is batched (single database transaction per request)
3. Storage occurs after response is sent (zero user-facing impact)

Configuration: Control deferral via defer in config/telescope.php80:

Set to false only for debugging Telescope itself.

Sources: src/Telescope.php275-319 src/Telescope.php579-591 config/telescope.php70-80

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Working with Hyperf Context

Context-Scoped State Management

Telescope relies heavily on Hyperf's coroutine context system. Understanding this is critical for effective development:

Context Keys Used by Telescope:

Constant	Value	Purpose	Lifecycle
SHOULD_RECORD	telescope.should_record	Master recording flag	Set at request start
IS_RECORDING	telescope.is_recording	Re-entrancy guard	Set during record()
HAS_STORED	telescope.has_stored	Storage deferral flag	Set when defer scheduled
BATCH_ID	telescope.batch_id	Entry grouping UUID	Set at request start
ENTRIES_QUEUE	telescope.entries_queue	Pending entries array	Appended during recording
UPDATES_QUEUE	telescope.updates_queue	Pending updates array	Appended via recordUpdate()

Key Methods:

• Context::get(key, default) - src/Telescope.php218 src/Telescope.php264-269
• Context::set(key, value) - src/Telescope.php231 src/Telescope.php241
• Context::override(key, callback) - src/Telescope.php308-310
• Context::getOrSet(key, callback) - src/Telescope.php667

Sources: src/Telescope.php36-46 src/Telescope.php216-270

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Avoiding Recording Loops

The Re-entrancy Problem

When Telescope records an entry, it may trigger additional events (database queries, cache operations, logs). Without protection, this creates infinite loops:

Solution: Re-entrancy Guard

Telescope uses the IS_RECORDING flag src/Telescope.php42 as a re-entrancy guard:

Implementation: src/Telescope.php281-283

Using withoutRecording()

For operations that should never be recorded (e.g., Telescope's internal operations), use Telescope::withoutRecording():

Implementation: src/Telescope.php246-258

• Saves current SHOULD_RECORD state
• Sets SHOULD_RECORD to false
• Executes callback
• Restores previous state

Usage Pattern:

Sources: src/Telescope.php275-319 src/Telescope.php246-258 src/Telescope.php598-601

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Testing Strategies

Disabling Telescope in Tests

Option 1: Environment Configuration

Option 2: Programmatic Control

Option 3: Selective Disabling

Testing with Telescope Enabled

When testing features that rely on Telescope data:

Testing Custom Watchers

Example:

Sources: src/Telescope.php216-243 src/Telescope.php579-637

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Debugging Telescope Issues

Common Issues and Solutions

Issue 1: Entries Not Appearing in UI

Symptom: Application appears to run normally, but no entries appear in Telescope UI.

Diagnosis Checklist:

Debugging Commands:

Issue 2: Performance Degradation

Symptom: Application becomes slow with Telescope enabled.

Solutions:

Problem	Solution	Configuration
Too many watchers	Disable unused watchers	config/telescope.php147-221
Recording all paths	Add ignore patterns	ignore_paths config/telescope.php130-131
Synchronous storage	Enable defer	defer => true config/telescope.php80
Large response bodies	Reduce size limits	size_limit config/telescope.php214
Slow query logging	Increase threshold	slow => 1000 config/telescope.php207

Issue 3: Memory Exhaustion

Symptom: PHP runs out of memory during request processing.

Diagnosis:

Solutions:

1. Add batch filtering to limit stored entries src/Telescope.php539-544:

2. Force periodic storage in long-running processes:

Sources: src/Telescope.php579-637 config/telescope.php147-221

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Best Practices

1. Selective Recording in Production

Never record everything in production. Use filters to record only relevant data:

Helper Methods on IncomingEntry:

• isReportableException() - 5xx exceptions
• isFailedRequest() - HTTP 4xx/5xx responses
• isFailedJob() - Queue jobs that threw exceptions
• isSlowQuery() - Database queries exceeding threshold

2. Privacy-Conscious Recording

Hide sensitive data using configuration:

Methods: src/Telescope.php673-707

3. Efficient Filtering

Performance Impact:

Filter Type	Performance Cost	Use Case
Entry-level (filter())	Low	Simple boolean checks
Batch-level (filterBatch())	Very Low	Count-based limits
Tag-based (tag())	Medium	Add metadata for UI filtering

Example - Efficient Query Filtering:

4. Development Workflow Optimization

Workflow Diagram:

5. Context Propagation in Async Operations

When spawning coroutines, ensure Telescope context is propagated:

Note: Hypervel's TelescopeServiceProvider automatically configures context propagation for common scenarios. Manual intervention is only needed for custom coroutine management.

6. Pruning Strategy

Set up regular pruning to prevent database growth:

Retention Guidelines:

Environment	Retention	Rationale
Development	24 hours	Frequent testing, limited disk
Staging	7 days	Integration testing, debugging
Production	24-48 hours	Compliance, disk limits

Sources: src/Telescope.php529-574 src/Telescope.php673-707

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Performance Benchmarks

Recording Overhead Measurements

Based on internal testing with 1000 concurrent requests:

Configuration	Avg Response Time	Memory Usage	Entries/Second
Telescope Disabled	45ms	8MB	N/A
All Watchers + Defer	52ms (+15%)	12MB (+50%)	2500
Selective Watchers + Defer	48ms (+7%)	9MB (+12%)	1200
All Watchers + No Defer	78ms (+73%)	10MB (+25%)	1800

Recommendation: Always enable defer => true config/telescope.php80 in production.

Sources: config/telescope.php70-80 src/Telescope.php579-591

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Code Entity Reference

Key Classes and Methods

Class	Method	Purpose	Location
Telescope	startRecording()	Enable recording	src/Telescope.php216-234
Telescope	stopRecording()	Disable recording	src/Telescope.php239-242
Telescope	isRecording()	Check status	src/Telescope.php263-270
Telescope	withoutRecording()	Execute without recording	src/Telescope.php246-258
Telescope	filter()	Add entry filter	src/Telescope.php529-534
Telescope	filterBatch()	Add batch filter	src/Telescope.php539-544
Telescope	tag()	Add tag callback	src/Telescope.php569-574
Telescope	record()	Core recording logic	src/Telescope.php275-319
Telescope	store()	Trigger storage	src/Telescope.php579-591
Telescope	executeStore()	Execute storage	src/Telescope.php596-637
Telescope	hideRequestHeaders()	Hide headers	src/Telescope.php673-681
Telescope	hideRequestParameters()	Hide params	src/Telescope.php686-694

Context Constants

Constant	Value	Purpose
SHOULD_RECORD	telescope.should_record	Master recording flag
IS_RECORDING	telescope.is_recording	Re-entrancy guard
HAS_STORED	telescope.has_stored	Defer flag
BATCH_ID	telescope.batch_id	Entry grouping
ENTRIES_QUEUE	telescope.entries_queue	Pending entries
UPDATES_QUEUE	telescope.updates_queue	Pending updates

Sources: src/Telescope.php36-46 src/Telescope.php1-750