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separating tag movies from tag
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@brunoczim
brunoczim committed Nov 6, 2020
1 parent 5872920 commit e71ac19
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Showing 5 changed files with 319 additions and 294 deletions.
2 changes: 2 additions & 0 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ HEADERS = src/error.h \
src/trie.h \
src/movies.h \
src/users.h \
src/tags/movies.h \
src/tags.h \
src/database.h \
src/shell.h
Expand All @@ -78,6 +79,7 @@ MOVIEDB_OBJS = $(OBJ_DIR)/main.o \
$(OBJ_DIR)/id.o \
$(OBJ_DIR)/movies.o \
$(OBJ_DIR)/users.o \
$(OBJ_DIR)/tags/movies.o \
$(OBJ_DIR)/tags.o \
$(OBJ_DIR)/database/loading.o \
$(OBJ_DIR)/database/movie_query.o \
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273 changes: 4 additions & 269 deletions src/tags.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,95 +5,6 @@

#define MAX_LOAD 0.5

/**
* Range of a list in a quicksort implementation. Only quicksort internal code
* is allowed to touch this.
*/
struct sort_range {
/**
* Start index, inclusive.
*/
size_t start;
/**
* End index, exclusive.
*/
size_t end;
};

/**
* Stack used by the quicksort-related functions.
*/
struct sort_stack {
/**
* The elements of the stack. Only quicksort internal code is allowed to
* touch this.
*/
struct sort_range *ranges;
/**
* Number of elements in the stack. Only quicksort internal code is allowed
* to touch this.
*/
size_t length;
/**
* How many elements the stack can store. Only quicksort internal code is
* allowed to * touch this.
*/
size_t capacity;
};

/**
* Initalizes the stack with the given capacity.
*/
static void sort_init(
struct sort_stack *restrict stack,
size_t capacity,
struct error *error);

/**
* Pushes the given range to the stack. Only internal quicksort code is allowed
* to touch this.
*/
static void sort_push(
struct sort_stack *restrict stack,
struct sort_range const *restrict range,
struct error *restrict error);

/**
* Tries to pop from the sort stack into range_out, returns whether the pop
* happened. Only internal quicksort code is allowed to touch this.
*/
static bool sort_pop(
struct sort_stack *restrict stack,
struct sort_range *restrict range_out);

/**
* Destroys the sort stack.
*/
static void sort_destroy(struct sort_stack *restrict stack);

/**
* Chooses the median as the pivot of an iteration of quicksort.
*/
static db_id_t sort_choose_median(
struct tag_movie_list *restrict list,
struct sort_range const *range);

/**
* Performs the hoare partition on the given list, given the pivot.
*/
static size_t sort_partition_hoare(
struct tag_movie_list *restrict list,
db_id_t pivot,
struct sort_range const *range);

/**
* Performs quicksort on the given movie list.
*/
static void quicksort(
struct tag_movie_list *restrict list,
struct sort_stack *restrict stack,
struct error *restrict error);

/**
* Initializes a tag by allocating a tag in the heap.
*/
Expand Down Expand Up @@ -192,19 +103,19 @@ void tags_sort_movies(
struct tags_table *restrict table,
struct error *restrict error)
{
struct sort_stack stack;
struct tag_movies_sort_stack stack;
size_t i = 0;

sort_init(&stack, 2, error);
tag_movies_sort_init(&stack, 2, error);

if (error->code == error_none) {
while (i < table->capacity && error->code == error_none) {
if (table->entries[i] != NULL) {
quicksort(&table->entries[i]->movies, &stack, error);
tag_movies_sort(&table->entries[i]->movies, &stack, error);
}
i++;
}
sort_destroy(&stack);
tag_movies_sort_destroy(&stack);
}
}

Expand All @@ -223,182 +134,6 @@ void tags_destroy(struct tags_table *restrict table)
db_free(table->entries);
}

bool tag_movies_contain(
struct tag_movie_list const *restrict movies,
db_id_t movieid)
{
bool found;
size_t low, high, mid;

low = 0;
high = movies->length;
found = false;

while (low < high && !found) {
mid = low + (high - low) / 2;

if (movies->entries[mid] < movieid) {
low = mid + 1;
} else if (movies->entries[mid] > movieid) {
high = mid;
} else {
found = true;
}
}

return found;
}

static void sort_init(
struct sort_stack *restrict stack,
size_t capacity,
struct error *error)
{
stack->ranges = db_alloc(sizeof(struct sort_range) * capacity, error);
stack->length = 0;
stack->capacity = capacity;
}

static void sort_push(
struct sort_stack *restrict stack,
struct sort_range const *restrict range,
struct error *restrict error)
{
struct sort_range *new_ranges;
size_t new_cap;

if (stack->length == stack->capacity) {
new_cap = stack->capacity * 2;
if (new_cap == 0) {
new_cap = 1;
}
new_ranges = db_realloc(
stack->ranges,
sizeof(struct sort_range) * new_cap,
error);

if (error->code == error_none) {
stack->capacity = new_cap;
stack->ranges = new_ranges;
}
}

stack->ranges[stack->length] = *range;
stack->length++;
}

static bool sort_pop(
struct sort_stack *restrict stack,
struct sort_range *restrict range_out)
{
if (stack->length == 0) {
return false;
}
stack->length--;
*range_out = stack->ranges[stack->length];
return true;
}

static void sort_destroy(struct sort_stack *restrict stack)
{
db_free(stack->ranges);
}

static db_id_t sort_choose_median(
struct tag_movie_list *restrict list,
struct sort_range const *range)
{
db_id_t tmp;
size_t half = range->start + (range->end - range->start) / 2;

if (list->entries[half] > list->entries[range->end - 1]) {
tmp = list->entries[half];
list->entries[half] = list->entries[range->end - 1];
list->entries[range->end - 1] = tmp;
}

if (list->entries[half] < list->entries[range->start]) {
tmp = list->entries[half];
list->entries[half] = list->entries[range->start];
list->entries[range->start] = tmp;

if (list->entries[half] > list->entries[range->end - 1]) {
tmp = list->entries[half];
list->entries[half] = list->entries[range->end - 1];
list->entries[range->end - 1] = tmp;
}
}

return list->entries[half];
}

static size_t sort_partition_hoare(
struct tag_movie_list *restrict list,
db_id_t pivot,
struct sort_range const *range)
{
db_id_t tmp;
size_t low = range->start;
size_t high = range->end - 1;
bool elems_left = true;

while (elems_left) {
do {
low++;
} while (list->entries[low] < pivot);

do {
high--;
} while (list->entries[high] > pivot);

elems_left = low < high;

if (elems_left) {
tmp = list->entries[low];
list->entries[low] = list->entries[high];
list->entries[high] = tmp;
}
}

return high + 1;
}

static void quicksort(
struct tag_movie_list *restrict list,
struct sort_stack *restrict stack,
struct error *restrict error)
{
struct sort_range curr, lower, upper;
size_t split;
db_id_t pivot;

curr.start = 0;
curr.end = list->length;

if (curr.end - curr.start > 1) {
sort_push(stack, &curr, error);
}

while (error->code == error_none && sort_pop(stack, &curr)) {
pivot = sort_choose_median(list, &curr);
split = sort_partition_hoare(list, pivot, &curr);

lower.start = curr.start;
lower.end = split;

if (lower.end - lower.start > 1) {
sort_push(stack, &lower, error);
}

upper.start = split;
upper.end = curr.end;

if (upper.end - upper.start > 1) {
sort_push(stack, &upper, error);
}
}
}

static struct tag *tag_init(
struct tag_csv_row *restrict tag_row,
struct error *restrict error)
Expand Down
26 changes: 1 addition & 25 deletions src/tags.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,32 +3,12 @@

#include "id.h"
#include "csv/tag.h"
#include "tags/movies.h"

/**
* This file exports items related to tags.
*/

/**
* The movies associated with a tag.
*/
struct tag_movie_list {
/**
* Array of entries. Only internal tags hash table code is allowed
* to update this value. Reading is fine.
*/
db_id_t *entries;
/**
* How much entries are stored here. Only internal tags hash table code is
* allowed to update this value. Reading is fine.
*/
size_t length;
/**
* How many entries we can currently store. Only internal tags hash table
* code is allowed to touch this value.
*/
size_t capacity;
};

/**
* A tag's data.
*/
Expand Down Expand Up @@ -104,8 +84,4 @@ void tags_sort_movies(
*/
void tags_destroy(struct tags_table *restrict table);

bool tag_movies_contain(
struct tag_movie_list const *restrict movies,
db_id_t movieid);

#endif
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