# hipDNN Environment Configuration

This document describes the environment variables and runtime configuration options for hipDNN.

## Table of Contents

- [Environment Variables](#environment-variables)
  - [Plugin Discovery](#plugin-discovery)
  - [Heuristic Policy Selection](#heuristic-policy-selection)
  - [Logging Variables](#logging-variables)
  - [MIOpen Plugin Logging](#miopen-plugin-logging)
  - [Test Configuration](#test-configuration)
- [Logging Configuration APIs](#logging-configuration-apis)
  - [User Log Callbacks](#user-log-callbacks)
  - [Log Level APIs](#log-level-apis)
- [Error Handling](#error-handling)

---

## Environment Variables

### Plugin Discovery

hipDNN supports a plugin architecture for both execution engines and heuristic policies. Plugins are automatically discovered at runtime from configurable search paths.

#### HIPDNN_PLUGIN_DIR

Specifies the directory path where hipDNN will search for engine plugins (shared libraries that provide operation implementations).

| Value      | Description                                            |
|------------|--------------------------------------------------------|
| (unset)    | Uses default path: `hipdnn_plugins/engines/` (relative to current working directory) |
| `<path>`   | Search for engine plugins in the specified directory  |

When set, this variable completely overrides the default search path. The path can be absolute or relative to the current working directory.

**Example:**
```bash
export HIPDNN_PLUGIN_DIR=/opt/rocm/lib/hipdnn/plugins/engines
```

**Notes:**
- Engine plugins must implement the Engine Plugin API (see `EnginePluginApi.h`)
- Plugin libraries are typically named `libhipdnn_provider_*.so` (Linux) or `hipdnn_provider_*.dll` (Windows)
- Only plugins whose API version major matches `HIPDNN_ENGINE_API_VERSION_MAJOR` (declared in `hipdnn_plugin_sdk/engine_api_version.h`) will be loaded
- See the [Plugin Development Guide](PluginDevelopment.md) for details on creating engine plugins

#### HIPDNN_HEURISTIC_PLUGIN_DIR

Specifies the directory path where hipDNN will search for heuristic plugins (shared libraries that provide operation selection policies).

| Value      | Description                                            |
|------------|--------------------------------------------------------|
| (unset)    | Uses default path: `hipdnn_plugins/heuristics/` (relative to current working directory) |
| `<path>`   | Search for heuristic plugins in the specified directory |

When set, this variable completely overrides the default search path. The path can be absolute or relative to the current working directory.

**Example:**
```bash
export HIPDNN_HEURISTIC_PLUGIN_DIR=/opt/rocm/lib/hipdnn/plugins/heuristics
```

**Notes:**
- Heuristic plugins must implement the Heuristic Plugin API (see `HeuristicsPluginApi.h`)
- Heuristic plugins have independent API versioning from engine plugins
- Only plugins with API version matching the Heuristic API major version will be loaded
- Each heuristic plugin must provide a unique policy ID and policy name
- See the [Plugin Development Guide](PluginDevelopment.md) for details on creating heuristic plugins

### Heuristic Policy Selection

hipDNN's heuristic framework selects an engine for each graph by running a configurable list of selection policies (the *outer loop*). The following variables tune that loop and the behavior of two built-in policies.

#### HIPDNN_HEUR_POLICY_ORDER

Overrides the heuristic policy order for the outer loop. Read by every `EngineHeuristicDescriptor::finalize()` call.

| Value      | Description                                                |
|------------|------------------------------------------------------------|
| (unset)    | Use the descriptor's `HIPDNN_ATTR_ENGINEHEUR_POLICY_ORDER_EXT` attribute if set; otherwise fall back to the built-in default `[SelectionHeuristic::Config, SelectionHeuristic::StaticOrdering]`. |
| `<list>`   | Comma-separated tokens consulted in the order written. Each token is either a policy name (hashed via `policyNameToId`) or a raw decimal int64 policy ID. Whitespace around tokens is trimmed; empty tokens are skipped. |

This variable has the **highest priority** — it overrides both the descriptor attribute and the built-in default.

**Example:**
```bash
# By name
export HIPDNN_HEUR_POLICY_ORDER="SelectionHeuristic::Config,SelectionHeuristic::StaticOrdering"

# By raw ID (or mixed names + IDs)
export HIPDNN_HEUR_POLICY_ORDER="-1234567890123456789,SelectionHeuristic::StaticOrdering"
```

#### HIPDNN_HEUR_CONFIG_PATH

Path to a JSON rule file consumed by the `SelectionHeuristic::Config` built-in policy. The file maps convolution op + tensor-shape patterns to a preferred engine name; the policy walks conv-like nodes in the serialized graph and, on the first matching rule, reorders the candidate engines so the chosen one runs first. Re-read on every `Finalize` invocation — there is no process-wide cache.

| Value      | Description                                                |
|------------|------------------------------------------------------------|
| (unset)    | The `SelectionHeuristic::Config` policy declines, allowing subsequent policies to run. |
| `<path>`   | Absolute or working-directory-relative path to a JSON rule file. |

If the file is missing, unreadable, fails to parse, no rule matches, or the matched engine name is not among the current candidates, the policy declines (so the outer loop continues with the next policy).

**Example:**
```bash
export HIPDNN_HEUR_CONFIG_PATH=/etc/hipdnn/engine_overrides.json
```

#### HIPDNN_HEUR_FALLBACK_ENGINE_ORDER

Replaces the built-in ordering used by `SelectionHeuristic::StaticOrdering`. When set, **only** engines named here are eligible — anything else is dropped from the candidate list.

| Value      | Description                                                |
|------------|------------------------------------------------------------|
| (unset)    | Use the built-in static ordering (MIOpen-first, deterministic engines last). |
| `<list>`   | Comma-separated engine names, applied in the order written. Whitespace is trimmed and empty tokens are skipped. |

Engine names that are not among the current candidates are silently skipped. If no listed engine matches any candidate, the policy declines so the outer loop can try the next plugin.

**Example:**
```bash
export HIPDNN_HEUR_FALLBACK_ENGINE_ORDER="MIOpenConvolutionFwdEngine,HipBLASLtMatmulEngine"
```

### Logging Variables

hipDNN provides the following environment variables to control logging behavior:
#### HIPDNN_LOG_LEVEL

Sets the minimum severity that will be emitted. Levels are inclusive: choosing a level enables messages at that level and all higher severities.

| Level  | Description                                                |
|--------|------------------------------------------------------------|
| `off`  | Disables all logging (default)                             |
| `info` | General informational messages                             |
| `warn` | Potential issues that do not interrupt execution           |
| `error`| Recoverable errors that may affect results or performance  |
| `fatal`| Unrecoverable errors; the operation will not continue      |

**Example:**
```bash
export HIPDNN_LOG_LEVEL=info
```

#### HIPDNN_LOG_FILE

Specifies the file path where logs will be **appended**. If not set, logs are written to `stderr`.

**Example:**
```bash
export HIPDNN_LOG_FILE=/path/to/hipdnn.log
```

#### HIPDNN_LOG_GRAPH_DIR

Controls graph structure logging. When set to a non-empty directory path, graphs are written as JSON files during finalization.

| Value      | Description                                            |
|------------|--------------------------------------------------------|
| (unset)    | Graph logging disabled (default)                       |
| `<path>`   | Write graph structures as JSON files to the given directory |

Graph JSON files are written to the directory specified by `HIPDNN_LOG_GRAPH_DIR`. If the directory does not exist, it is created automatically. Relative paths are resolved against the current working directory. Files are named `graph_<hash>.json` where `<hash>` is derived from the graph content, ensuring identical graphs are not duplicated.

This variable is independent of `HIPDNN_LOG_LEVEL` and `HIPDNN_LOG_FILE`.

**Example:**
```bash
export HIPDNN_LOG_GRAPH_DIR=/tmp/hipdnn_graphs
```

### MIOpen Plugin Logging

> [!TIP]
> 💡 When using the MIOpen Provider Plugin, you can use MIOpen-specific environment variables to control the underlying library's logging behavior.

For more details about MIOpen logging, see the latest [MIOpen Debug and Logging documentation](https://rocm.docs.amd.com/projects/MIOpen/en/develop/how-to/debug-log.html). All MIOpen environment variables remain compatible with hipDNN's MIOpen Provider Plugin.

### Test Configuration

#### HIPDNN_GLOBAL_TEST_SEED

Controls the random number generator seed used across hipDNN tests. This allows for reproducible test runs or full randomization when needed.

| Value        | Description                                                |
|--------------|------------------------------------------------------------|
| (not set)    | Uses default seed value of `1` (default behavior)         |
| `<number>`   | Uses the specified numeric seed (e.g., `42`, `12345`)     |
| `RANDOM`     | Generates a random seed using `std::random_device`        |

> [!NOTE]
> The `RANDOM` value is case-insensitive (`random`, `Random`, `RANDOM` all work).

**Examples:**
```bash
# Use a specific seed for consistent results
export HIPDNN_GLOBAL_TEST_SEED=42

# Use default seed (1) for reproducible tests
unset HIPDNN_GLOBAL_TEST_SEED

# Use random seed for each test run
export HIPDNN_GLOBAL_TEST_SEED=RANDOM
```

**Best Practices:**
- Use the default seed (1) for CI/CD pipelines to ensure consistent test results
- Use a specific numeric seed when debugging to reproduce exact test conditions
- Use `RANDOM` during development to catch edge cases with different data patterns

---


## Logging Configuration APIs

### User Log Callbacks

One or more user callback functions can be registered to receive log messages from the hipDNN library. User callbacks do not replace console/file logging, rather they provide an additional parallel method to receive log messages.

Each callback is uniquely identified by the composite key `(callback, userHandle)`, which allows registering the same callback function multiple times with different user handles (e.g., for different logging destinations).

#### Callback Signature

User callbacks must conform to the following C signature:

```c
typedef void (*hipdnnUserLogCallback_t)(hipdnnUserLogCallbackHandle_t userHandle,
                                        hipdnnSeverity_t severity,
                                        const char* message);
```

- `userHandle` — The opaque user-provided pointer passed back on each invocation
- `severity` — The severity level of the log message
- `message` — The formatted log message (null-terminated string)

#### Registering a Callback

The frontend API function `setUserLogCallback()` registers, updates, or removes a callback:

```cpp
Error setUserLogCallback(hipdnnUserLogCallback_t callback,
                         hipdnnSeverity_t minLevel,
                         LogCallbackMode mode,
                         hipdnnUserLogCallbackHandle_t userHandle);
```

**Parameters:**
- `callback` — The callback function to invoke (must be non-null)
- `minLevel` — Minimum severity level for messages delivered to this callback. Use `HIPDNN_SEV_OFF` to remove the callback.
- `mode` — `LogCallbackMode::ASYNC` (default, non-blocking) or `LogCallbackMode::SYNC` (blocking)
- `userHandle` — Non-null opaque pointer passed to the callback and used as part of the unique ID

**Behavior:**
- If `(callback, userHandle)` is not yet registered: **adds** a new registration
- If `(callback, userHandle)` is already registered: **updates** the level and/or mode
- If `minLevel` is `HIPDNN_SEV_OFF`: **removes** the registration

> [!NOTE]
> * The messages delivered to the callback are also subject to the global log level set by the `HIPDNN_LOG_LEVEL` environment variable or the `setGlobalLogLevel()` API. A callback registered at `HIPDNN_SEV_INFO` will not receive info-level messages if the global level is set to `HIPDNN_SEV_WARN` or higher.
> * The hipDNN logger has an internal log message queue of 8192 messages. Once the message queue is full, the
> hipDNN library will block on subsequent logging calls until space is made available in the queue. The
> callbacks must ensure that they are consuming messages and returning promptly to avoid stalling hipDNN.

#### Callback Modes

| Mode | Description |
|------|-------------|
| `LogCallbackMode::ASYNC` | Callback is invoked on a background worker thread. hipDNN is not blocked while the callback runs. Recommended for production use. |
| `LogCallbackMode::SYNC` | Callback is invoked on the calling thread. hipDNN blocks until the callback returns. Recommended only for debugging or testing. |

#### Removing a Callback

To remove a callback, call `setUserLogCallback()` with `minLevel` set to `HIPDNN_SEV_OFF`:

```cpp
auto error = setUserLogCallback(myCallback, HIPDNN_SEV_OFF, LogCallbackMode::ASYNC, myHandle);
```

After this call returns:
- The callback will not be invoked again
- Any pending async log messages for this callback are abandoned
- The caller can safely destroy data referenced by `userHandle`

#### Example

```cpp
#include <hipdnn_frontend.hpp>

using namespace hipdnn_frontend;

struct MyLogContext {
    std::ofstream logFile;
};

void myLogCallback(hipdnnUserLogCallbackHandle_t userHandle,
                   hipdnnSeverity_t severity,
                   const char* message) {
    auto* ctx = static_cast<MyLogContext*>(userHandle);
    ctx->logFile << message << std::endl;
}

// Register an async callback at INFO level
MyLogContext ctx{std::ofstream("my_log.txt")};
auto error = setUserLogCallback(&myLogCallback, HIPDNN_SEV_INFO,
                                LogCallbackMode::ASYNC, &ctx);

// ... use hipDNN APIs ...

// Remove the callback when done
error = setUserLogCallback(&myLogCallback, HIPDNN_SEV_OFF,
                           LogCallbackMode::ASYNC, &ctx);
// ctx can now be safely destroyed
```

### Log Level APIs

The following frontend API functions can programatically read and override the log level set by the `HIPDNN_LOG_LEVEL` environment variable:
```
Error getGlobalLogLevel(hipdnnSeverity_t& level)
```
Returns the current log level in use by the hipDNN library, including `HIPDNN_SEV_OFF` if logging is not enabled.
```
Error setGlobalLogLevel(hipdnnSeverity_t level)
```
Sets hipDNN to the specified log level. Use `HIPDNN_SEV_OFF` to disable logging.

## Error Handling

hipDNN provides functions for retrieving error information:

### Getting Error Strings

```c
// Convert status code to string
const char* error_str = hipdnnGetErrorString(status);

// Get detailed error message for the current thread
char message[HIPDNN_ERROR_STRING_MAX_LENGTH];
hipdnnGetLastErrorString(message, sizeof(message));
```

### Best Practices

1. Check return status codes from all hipDNN API calls
2. Use `hipdnnGetLastErrorString` for detailed error context
3. Enable appropriate logging levels during development and debugging
4. Configure logging to files for production deployments