Program State Recreation via Embedded Provenance Counters
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Solution Overview
Problem
Existing methods for determining the provenance of computed results in computer programs are inefficient, relying on programmer intervention and resource-intensive logging or event sourcing, which do not provide complete traceability of intermediate values and require active maintenance.
Innovation Solution
A system that uses step counters, creation counters, update counters, and stack counters to embed provenance information into program values, allowing for the recreation of program states and tracing the origin of values through time without programmer intervention, using a replay log and decoupled evaluators to capture and replay non-deterministic function calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If logging statements are inserted into the program to trace execution, then program activity can be traced, but programmer discipline and active maintenance are required and logging is costly in terms of developer resources
Solution Approach 1:
The system automatically traces program execution by instrumenting the program to self-record intermediate values and provenance information without requiring programmer intervention. The program executes normally while the system captures execution state, variable values, and data flow automatically, eliminating the need for developers to manually add logging statements.
Solution Approach 2:
The system performs preliminary instrumentation of the program code before execution to set up automatic tracing. Counters and metadata are embedded in advance to track provenance information, so that during normal execution, all necessary trace data is automatically captured without requiring real-time programmer input or manual logging setup.
2Reliability
If event sourcing is used to record program outputs and inputs as structured events, then previous program states can be re-created, but active programmer participation is required to record all events
Solution Approach 1:
The program automatically records all execution events and state changes through built-in instrumentation. The system captures intermediate values, variable states, and execution flow automatically during program execution, eliminating the need for programmers to manually record events. The provenance tracking is self-executing and comprehensive.
Solution Approach 2:
The system extracts and separates the provenance tracking functionality from the main program logic. A dedicated tracing mechanism is implemented that independently captures execution data without requiring programmer involvement in the recording process. This extracted tracing system operates autonomously to record all necessary events for state recreation.
3Loss of information
If intermediate variable values are retained in memory, then provenance information is preserved, but computer resources are consumed
Solution Approach 1:
The system selectively retains provenance information based on local requirements. Rather than keeping all intermediate values in memory indefinitely, the system preserves only the specific values and states necessary for provenance tracking at each execution point. Metadata and counters are stored locally with the relevant data, optimizing memory usage by retaining only essential provenance information.
Solution Approach 2:
Provenance information is segmented and organized by execution context, variable, and time point. The system divides the trace data into discrete, manageable units that can be stored efficiently. By segmenting the provenance data structure, the system reduces overall memory consumption while maintaining the ability to retrieve specific intermediate values when needed for state recreation.
Data Source
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AI summary
There is provided a computer implemented method, a system for performing the method, and a computer program for recreating a program state. In one aspect, the invention comprises associating a step counter with respective points in the progress of a program's execution and generating a snapshot by storing the set of program values associated with a first step counter value. The state of the program is subsequently recreated by recreating the program state from the snapshot preceding the point in the progress of the program execution associated with a query step counter value and executing the program from the recreated state of the program to the point in the progress of the program execution associated with the second index reference value, including using previously stored non-deterministic values.