Implementation and draft integration of binary expression tree

This replaces the stack-based calculator with a binary expression tree. The tree is constructed only once per metric when a perfgroup is read and can be evaluated arbitrarily often.

Author: breiters

src/calculator_exptree.c

@@ -0,0 +1,271 @@
+#include <bstrlib.h>
+#include <bstrlib_helper.h>
+#include <perfgroup.h> /* CounterList */
+#include "calculator_exptree.h"
+
+#include <ctype.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+struct exptree_node {
+    struct exptree_node *left;  // Left child
+    struct exptree_node *right; // Right child
+
+    double value; // Operand value (if it's a number)
+    char  *counter_name;
+    char   operator; // Operator: '+', '-', '*', '/'
+};
+
+// Forward declarations
+static struct exptree_node *_make_expression_tree(const char **expr);
+static struct exptree_node *_make_term_tree(const char **expr);
+static struct exptree_node *_make_factor_tree(const char **expr);
+
+#define NODE_NULL_VALUE    0.0
+#define NODE_NULL_OPERATOR '\0'
+
+static void _skip_spaces(const char **expr)
+{
+    while (isspace(**expr)) {
+        (*expr)++;
+    }
+}
+
+// Set value and create a leaf node
+static struct exptree_node *_make_value_node(double value)
+{
+    struct exptree_node *node = malloc(sizeof(struct exptree_node));
+    if (!node) {
+        return NULL;
+    }
+    *node = (struct exptree_node){.left         = NULL,
+                                  .right        = NULL,
+                                  .value        = value,
+                                  .counter_name = NULL,
+                                  .operator= NODE_NULL_OPERATOR };
+    return node;
+}
+
+// Set counter and create a leaf node
+static struct exptree_node *_make_counter_node(char *counter)
+{
+    struct exptree_node *node =
+        (struct exptree_node *)malloc(sizeof(struct exptree_node));
+    if (!node) {
+        return NULL;
+    }
+    *node = (struct exptree_node){.left         = NULL,
+                                  .right        = NULL,
+                                  .value        = NODE_NULL_VALUE,
+                                  .counter_name = counter,
+                                  .operator= NODE_NULL_OPERATOR };
+    return node;
+}
+
+// Parse an operator and create an operator node
+static struct exptree_node *
+_make_operator_node(char operator, struct exptree_node *left, struct exptree_node *right)
+{
+    struct exptree_node *node =
+        (struct exptree_node *)malloc(sizeof(struct exptree_node));
+    if (!node) {
+        return NULL;
+    }
+    *node = (struct exptree_node){.left         = left,
+                                  .right        = right,
+                                  .value        = NODE_NULL_VALUE,
+                                  .counter_name = NULL,
+                                  .operator= operator};
+    return node;
+}
+
+// Parse factors: numbers or subexpressions in parentheses
+static struct exptree_node *_make_factor_tree(const char **expr)
+{
+    _skip_spaces(expr);
+    if (**expr == '(') {
+        (*expr)++; // Skip '('
+        // Recursively parse the subexpression:
+        struct exptree_node *subtree = _make_expression_tree(expr);
+        _skip_spaces(expr);
+        if (**expr == ')') {
+            (*expr)++; // Skip ')'
+        } else {
+            fprintf(stderr, "Error: Mismatched parentheses\n");
+            exit(EXIT_FAILURE);
+        }
+        return subtree;
+    } else {
+        char  *endptr;
+        double value = strtod(*expr, &endptr);
+        if (*expr == endptr) {
+            // no conversion performed
+            char *counter_name;
+            if (sscanf(*expr, " %m[^()+-*/ \n] %*s", &counter_name) == 1) {
+                *expr += strlen(counter_name);
+                return _make_counter_node(counter_name);
+            } else {
+                fprintf(stderr, "Error: Could not parse: %s\n", *expr);
+                exit(EXIT_FAILURE);
+            }
+        }
+        *expr = endptr;
+        return _make_value_node(value);
+    }
+}
+
+// Parse terms: handles multiplication and division
+static struct exptree_node *_make_term_tree(const char **expr)
+{
+    struct exptree_node *left = _make_factor_tree(expr);
+    while (1) {
+        _skip_spaces(expr);
+        if (**expr == '*' || **expr == '/') {
+            char operator= ** expr;
+            (*expr)++;
+            struct exptree_node *right = _make_factor_tree(expr);
+            left                       = _make_operator_node(operator, left, right);
+        } else {
+            break;
+        }
+    }
+    return left;
+}
+
+// Parse expressions: handles addition and subtraction
+static struct exptree_node *_make_expression_tree(const char **expr)
+{
+    struct exptree_node *left = _make_term_tree(expr);
+    while (1) {
+        _skip_spaces(expr);
+        if (**expr == '+' || **expr == '-') {
+            char operator= ** expr;
+            (*expr)++;
+            struct exptree_node *right = _make_term_tree(expr);
+            left                       = _make_operator_node(operator, left, right);
+        } else {
+            break;
+        }
+    }
+    return left;
+}
+
+struct exptree_node *make_expression_tree(const char *expr)
+{
+    return _make_expression_tree(&expr);
+}
+
+// Print the expression tree in in-order traversal
+static void _print_expression_tree(const struct exptree_node *node)
+{
+    if (!node) {
+        return;
+    }
+    if (node->operator) {
+        printf("(");
+    }
+    _print_expression_tree(node->left);
+    if (node->operator) {
+        printf(" %c ", node->operator);
+    } else if (node->counter_name) {
+        printf("%s", node->counter_name);
+    } else {
+        printf("%g", node->value);
+    }
+    _print_expression_tree(node->right);
+    if (node->operator) {
+        printf(")");
+    }
+}
+
+// Print the expression tree in in-order traversal
+void print_expression_tree(const struct exptree_node *node)
+{
+    if (!node) {
+        printf("Empty expression tree\n");
+        return;
+    }
+    _print_expression_tree(node);
+    printf("\n");
+}
+
+// Free the memory used by the tree
+void free_expression_tree(struct exptree_node *node)
+{
+    if (!node) {
+        return;
+    }
+    free_expression_tree(node->left);
+    free_expression_tree(node->right);
+    free(node->counter_name);
+    free(node);
+}
+
+// Get node value
+static double _get_value(const struct exptree_node *node, const CounterList *clist)
+{
+    if (!node->counter_name) {
+        return node->value;
+    }
+
+    size_t len = strlen(node->counter_name);
+    
+    /* TODO: set counter index when making the counter node to avoid redundant search */
+    /*       only ok if order does not change */
+    for (int ctr = 0; clist->counters; ++ctr) {
+        const char *cname = bdata(clist->cnames->entry[ctr]);
+        
+        if (len == strlen(cname) && !strncmp(node->counter_name, cname, len)) {
+            const char *val_str = bdata(clist->cvalues->entry[ctr]);
+            /* TODO: why are counter values stored as strings instead of unsigned long
+             * long ? */
+            double val = strtod(val_str, NULL);
+            /* TODO error handling of strtod */
+            return val;
+        }
+    }
+
+    fprintf(stderr, "Error: counter not found: %s\n", node->counter_name);
+    return NODE_NULL_VALUE; // TODO: error handling
+}
+
+// Evaluate the expression tree recursively
+double evaluate_expression_tree(const struct exptree_node *node, const CounterList *clist)
+{
+    // TODO: maybe return NAN to indicate error ?
+    // need to check for NULL in child node evaluation in this case
+    if (!node) {
+        return 0.0;
+    }
+
+    // If it's a leaf node (number/counter), return its value
+    if (node->operator== NODE_NULL_OPERATOR) {
+        return _get_value(node, clist);
+    }
+
+    // Recursively evaluate left and right subtrees
+    double val_left  = evaluate_expression_tree(node->left, clist);
+    double val_right = evaluate_expression_tree(node->right, clist);
+
+    // Apply the operator
+    switch (node->operator) {
+    case '+':
+        return val_left + val_right;
+    case '-':
+        return val_left - val_right;
+    case '*':
+        return val_left * val_right;
+    case '/':
+        if (val_right == 0.0) {
+            fprintf(stderr, "Error: Division by zero\n");
+            exit(EXIT_FAILURE);
+        }
+        return val_left / val_right;
+    default:
+        fprintf(stderr, "Error: Unknown operator '%c'\n", node->operator);
+        exit(EXIT_FAILURE);
+    }
+}

src/includes/calculator_exptree.h

@@ -0,0 +1,19 @@
+// calculator_exptree.h
+
+struct exptree_node; // fwd declaration
+
+// cannot fwd declare CounterList because it was an anonymous struct (changed)
+// thus we named CounterList to avoid unnecessary cyclic inclusion dependency with:
+// #include "perfgroup.h"
+struct CounterList; // fwd declaration
+
+// TODO: documentation of interfaces
+// TODO: do we want "print_expression_tree"?
+
+extern struct exptree_node *make_expression_tree(const char *expr);
+
+extern void free_expression_tree(struct exptree_node *root);
+
+extern double evaluate_expression_tree(const struct exptree_node *node, const struct CounterList *clist);
+
+extern void print_expression_tree(const struct exptree_node *root);

src/includes/likwid.h

@@ -37,6 +37,8 @@
 
 #include <bstrlib.h>
 
+#include "calculator_exptree.h" // fwd declaration of struct exptree_node
+
 #define DEBUGLEV_ONLY_ERROR 0
 #define DEBUGLEV_INFO 1
 #define DEBUGLEV_DETAIL 2
@@ -1286,6 +1288,7 @@ typedef struct {
   int nmetrics;       /*!< \brief Number of metrics */
   char **metricnames; /*!< \brief Metric names */
   char **metricformulas; /*!< \brief Metric formulas */
+  struct exptree_node **metrictrees; /*!< \brief Metric expression trees */
   char *longinfo; /*!< \brief Descriptive text about the group or empty */
 } GroupInfo;
 

src/includes/perfgroup.h

@@ -34,6 +34,7 @@
 #include <bstrlib_helper.h>
 
 #include <likwid.h>
+#include "calculator_exptree.h"
 
 typedef enum {
     GROUP_NONE = 0,
@@ -54,7 +55,7 @@ static char* groupFileSectionNames[MAX_GROUP_FILE_SECTIONS] = {
     "LUA"
 };
 
-typedef struct {
+typedef struct CounterList {
     int counters; /*!< \brief Number of entries in the list */
     struct bstrList* cnames; /*!< \brief List of counter names */
     struct bstrList* cvalues; /*!< \brief List of counter values */
@@ -79,8 +80,7 @@ extern int update_clist(CounterList* clist, char* counter, double result);
 extern void destroy_clist(CounterList* clist);
 
 extern int calc_metric(char* formula, CounterList* clist, double *result);
-
-
+extern int calc_metric_new(const struct exptree_node* tree, const CounterList* clist, double *result);
 
 
 #endif /* PERFGROUP_H */